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Area formulas

Surveying · FE Reference Handbook section

Surveying
5 formulas
10 exam-style examples
~55 min
All Surveying lectures

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Trapezoidal rule area (single panel) — solve for area — Area formulas

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 32.0000 ft; offset 2 (h2) = 43.5000 ft; interval width (w) = 19.0000 ft, determine the area (A) in ft².

Given

  • offset1(h1)=32.0000ftoffset 1 (h_{1}) = 32.0000 ft
  • offset2(h2)=43.5000ftoffset 2 (h_{2}) = 43.5000 ft
  • intervalwidth(w)=19.0000ftinterval width (w) = 19.0000 ft

Find

area (A), in ft²

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=32.0000ft,offset2(h2)=43.5000ft,intervalwidth(w)=19.0000ftList the givens: offset 1 (h_{1}) = 32.0000 ft, offset 2 (h_{2}) = 43.5000 ft, interval width (w) = 19.0000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=717.3 ft²A = 717.3\ \text{ft²}
  6. Step 6 — Check: returning A = 717.3 ft² to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=717.3 ft²A = 717.3\ \text{ft²}

Why the other options are there

  • 1,435 — kept a factor of two that cancels in the correct rearrangement.
  • 358.6 — dropped that same factor in the other direction.
  • 789.0 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 2
Trapezoidal rule area (single panel) — solve for interval width — Area formulas (2)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 42.0000 ft; offset 2 (h2) = 18.0000 ft; area (A) = 1,215 ft², determine the interval width (w) in ft.

Given

  • offset1(h1)=42.0000ftoffset 1 (h_{1}) = 42.0000 ft
  • offset2(h2)=18.0000ftoffset 2 (h_{2}) = 18.0000 ft
  • area(A)=1,215ft2area (A) = 1,215 ft^{2}

Find

interval width (w), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except w is given, so isolate w symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that w stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=42.0000ft,offset2(h2)=18.0000ft,area(A)=1,215ft2List the givens: offset 1 (h_{1}) = 42.0000 ft, offset 2 (h_{2}) = 18.0000 ft, area (A) = 1,215 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    w=40.5000 ftw = 40.5000\ \text{ft}
  6. Step 6 — Check: returning w = 40.5000 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
w=40.5000 ftw = 40.5000\ \text{ft}

Why the other options are there

  • 81.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 20.2500 — dropped that same factor in the other direction.
  • 44.5500 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 3
Trapezoidal rule area (single panel) — solve for offset 1 — Area formulas (3)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 2 (h2) = 5.0000 ft; interval width (w) = 82.0000 ft; area (A) = 3,198 ft², determine the offset 1 (h1) in ft.

Given

  • offset2(h2)=5.0000ftoffset 2 (h_{2}) = 5.0000 ft
  • intervalwidth(w)=82.0000ftinterval width (w) = 82.0000 ft
  • area(A)=3,198ft2area (A) = 3,198 ft^{2}

Find

offset 1 (h1), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except h1 is given, so isolate h1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that h1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset2(h2)=5.0000ft,intervalwidth(w)=82.0000ft,area(A)=3,198ft2List the givens: offset 2 (h_{2}) = 5.0000 ft, interval width (w) = 82.0000 ft, area (A) = 3,198 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h1=73.0000 fth_{1} = 73.0000\ \text{ft}
  6. Step 6 — Check: returning h1 = 73.0000 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
h1=73.0000 fth_{1} = 73.0000\ \text{ft}

Why the other options are there

  • 146.0 — kept a factor of two that cancels in the correct rearrangement.
  • 36.5000 — dropped that same factor in the other direction.
  • 80.3000 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 4
Trapezoidal rule area (single panel) — solve for area (case 2) — Area formulas (4)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 47.0000 ft; offset 2 (h2) = 19.0000 ft; interval width (w) = 15.0000 ft, determine the area (A) in ft².

Given

  • offset1(h1)=47.0000ftoffset 1 (h_{1}) = 47.0000 ft
  • offset2(h2)=19.0000ftoffset 2 (h_{2}) = 19.0000 ft
  • intervalwidth(w)=15.0000ftinterval width (w) = 15.0000 ft

Find

area (A), in ft²

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=47.0000ft,offset2(h2)=19.0000ft,intervalwidth(w)=15.0000ftList the givens: offset 1 (h_{1}) = 47.0000 ft, offset 2 (h_{2}) = 19.0000 ft, interval width (w) = 15.0000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=495.0 ft²A = 495.0\ \text{ft²}
  6. Step 6 — Check: returning A = 495.0 ft² to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=495.0 ft²A = 495.0\ \text{ft²}

Why the other options are there

  • 990.0 — kept a factor of two that cancels in the correct rearrangement.
  • 247.5 — dropped that same factor in the other direction.
  • 544.5 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 5
Trapezoidal rule area (single panel) — solve for interval width (case 2) — Area formulas (5)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 46.5000 ft; offset 2 (h2) = 44.5000 ft; area (A) = 1,078 ft², determine the interval width (w) in ft.

Given

  • offset1(h1)=46.5000ftoffset 1 (h_{1}) = 46.5000 ft
  • offset2(h2)=44.5000ftoffset 2 (h_{2}) = 44.5000 ft
  • area(A)=1,078ft2area (A) = 1,078 ft^{2}

Find

interval width (w), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except w is given, so isolate w symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that w stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=46.5000ft,offset2(h2)=44.5000ft,area(A)=1,078ft2List the givens: offset 1 (h_{1}) = 46.5000 ft, offset 2 (h_{2}) = 44.5000 ft, area (A) = 1,078 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    w=23.6923 ftw = 23.6923\ \text{ft}
  6. Step 6 — Check: returning w = 23.6923 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
w=23.6923 ftw = 23.6923\ \text{ft}

Why the other options are there

  • 47.3846 — kept a factor of two that cancels in the correct rearrangement.
  • 11.8462 — dropped that same factor in the other direction.
  • 26.0615 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 6
Trapezoidal rule area (single panel) — solve for offset 1 (case 2) — Area formulas (6)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 2 (h2) = 9.0000 ft; interval width (w) = 37.0000 ft; area (A) = 2,645 ft², determine the offset 1 (h1) in ft.

Given

  • offset2(h2)=9.0000ftoffset 2 (h_{2}) = 9.0000 ft
  • intervalwidth(w)=37.0000ftinterval width (w) = 37.0000 ft
  • area(A)=2,645ft2area (A) = 2,645 ft^{2}

Find

offset 1 (h1), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except h1 is given, so isolate h1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that h1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset2(h2)=9.0000ft,intervalwidth(w)=37.0000ft,area(A)=2,645ft2List the givens: offset 2 (h_{2}) = 9.0000 ft, interval width (w) = 37.0000 ft, area (A) = 2,645 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h1=134.0 fth_{1} = 134.0\ \text{ft}
  6. Step 6 — Check: returning h1 = 134.0 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
h1=134.0 fth_{1} = 134.0\ \text{ft}

Why the other options are there

  • 267.9 — kept a factor of two that cancels in the correct rearrangement.
  • 66.9865 — dropped that same factor in the other direction.
  • 147.4 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 7
Trapezoidal rule area (single panel) — solve for area (case 3) — Area formulas (7)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 22.0000 ft; offset 2 (h2) = 19.5000 ft; interval width (w) = 22.0000 ft, determine the area (A) in ft².

Given

  • offset1(h1)=22.0000ftoffset 1 (h_{1}) = 22.0000 ft
  • offset2(h2)=19.5000ftoffset 2 (h_{2}) = 19.5000 ft
  • intervalwidth(w)=22.0000ftinterval width (w) = 22.0000 ft

Find

area (A), in ft²

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=22.0000ft,offset2(h2)=19.5000ft,intervalwidth(w)=22.0000ftList the givens: offset 1 (h_{1}) = 22.0000 ft, offset 2 (h_{2}) = 19.5000 ft, interval width (w) = 22.0000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=456.5 ft²A = 456.5\ \text{ft²}
  6. Step 6 — Check: returning A = 456.5 ft² to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=456.5 ft²A = 456.5\ \text{ft²}

Why the other options are there

  • 913.0 — kept a factor of two that cancels in the correct rearrangement.
  • 228.3 — dropped that same factor in the other direction.
  • 502.2 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 8
Trapezoidal rule area (single panel) — solve for interval width (case 3) — Area formulas (8)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 27.5000 ft; offset 2 (h2) = 43.0000 ft; area (A) = 1,168 ft², determine the interval width (w) in ft.

Given

  • offset1(h1)=27.5000ftoffset 1 (h_{1}) = 27.5000 ft
  • offset2(h2)=43.0000ftoffset 2 (h_{2}) = 43.0000 ft
  • area(A)=1,168ft2area (A) = 1,168 ft^{2}

Find

interval width (w), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except w is given, so isolate w symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that w stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=27.5000ft,offset2(h2)=43.0000ft,area(A)=1,168ft2List the givens: offset 1 (h_{1}) = 27.5000 ft, offset 2 (h_{2}) = 43.0000 ft, area (A) = 1,168 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    w=33.1348 ftw = 33.1348\ \text{ft}
  6. Step 6 — Check: returning w = 33.1348 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
w=33.1348 ftw = 33.1348\ \text{ft}

Why the other options are there

  • 66.2695 — kept a factor of two that cancels in the correct rearrangement.
  • 16.5674 — dropped that same factor in the other direction.
  • 36.4482 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 9
Trapezoidal rule area (single panel) — solve for offset 1 (case 3) — Area formulas (9)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 2 (h2) = 42.0000 ft; interval width (w) = 53.0000 ft; area (A) = 2,777 ft², determine the offset 1 (h1) in ft.

Given

  • offset2(h2)=42.0000ftoffset 2 (h_{2}) = 42.0000 ft
  • intervalwidth(w)=53.0000ftinterval width (w) = 53.0000 ft
  • area(A)=2,777ft2area (A) = 2,777 ft^{2}

Find

offset 1 (h1), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except h1 is given, so isolate h1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that h1 stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset2(h2)=42.0000ft,intervalwidth(w)=53.0000ft,area(A)=2,777ft2List the givens: offset 2 (h_{2}) = 42.0000 ft, interval width (w) = 53.0000 ft, area (A) = 2,777 ft^{2}
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    h1=62.7925 fth_{1} = 62.7925\ \text{ft}
  6. Step 6 — Check: returning h1 = 62.7925 ft to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
h1=62.7925 fth_{1} = 62.7925\ \text{ft}

Why the other options are there

  • 125.6 — kept a factor of two that cancels in the correct rearrangement.
  • 31.3962 — dropped that same factor in the other direction.
  • 69.0717 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

Example 10
Trapezoidal rule area (single panel) — solve for area (case 4) — Area formulas (10)

A surveying problem uses Trapezoidal rule area (single panel). Given offset 1 (h1) = 26.0000 ft; offset 2 (h2) = 13.5000 ft; interval width (w) = 59.0000 ft, determine the area (A) in ft².

Given

  • offset1(h1)=26.0000ftoffset 1 (h_{1}) = 26.0000 ft
  • offset2(h2)=13.5000ftoffset 2 (h_{2}) = 13.5000 ft
  • intervalwidth(w)=59.0000ftinterval width (w) = 59.0000 ft

Find

area (A), in ft²

Start with the thinking

  • The governing relation printed in this handbook section is Trapezoidal rule area (single panel).
  • Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Surveying items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3

    Listthegivens:offset1(h1)=26.0000ft,offset2(h2)=13.5000ft,intervalwidth(w)=59.0000ftList the givens: offset 1 (h_{1}) = 26.0000 ft, offset 2 (h_{2}) = 13.5000 ft, interval width (w) = 59.0000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    A=1165 ft²A = 1165\ \text{ft²}
  6. Step 6 — Check: returning A = 1,165 ft² to

    A=(h1+h2)/2×wA = (h_1 + h_2)/2 \times w

    reproduces the given quantities, and both sides carry the same units.

Answer:
A=1165 ft²A = 1165\ \text{ft²}

Why the other options are there

  • 2,331 — kept a factor of two that cancels in the correct rearrangement.
  • 582.6 — dropped that same factor in the other direction.
  • 1,282 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Surveying → Area formulas

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