Straight Line
Mathematics · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- The general form of the equation is
- The standard form of the equation is
- which is also known as the slope-intercept form.
- The angle between lines with slopes m1 and m2 is
- The distance between two points is
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.
A mathematics problem uses Slope–intercept line. Given slope (m) = 0.9000; x-value (x) = 5.5000; intercept (b) = -9.0000, determine the y-value (y).
Given
Find
y-value (y)
Start with the thinking
- The governing relation printed in this handbook section is Slope–intercept line.
- Everything except y is given, so isolate y 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.
- Mathematics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that y stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning y = -4.0500 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- -8.1000 — kept a factor of two that cancels in the correct rearrangement.
- -2.0250 — dropped that same factor in the other direction.
- -4.4550 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Mathematics → Straight Line
A designer checks the slope of a straight line on a site grading plan. Given x1 (x1) = 5.0000; x2 (x2) = 9.0000; y1 (y1) = 6.5000; y2 (y2) = 26.0000, determine the slope (m).
Given
Find
slope (m)
Start with the thinking
- The governing relation printed in this handbook section is Straight Line — two-point slope.
- Everything except m is given, so isolate m 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.
- The FE Handbook Straight Line relation gives the slope through two points on a line.
Figure 2 — schematic for Straight Line — two-point slope — solve for slope — Straight Line (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for m:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning m = 4.8750 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 9.7500 — kept a factor of two that cancels in the correct rearrangement.
- 2.4375 — dropped that same factor in the other direction.
- 5.3625 — rounded an intermediate value before the final step.
Reference: FE Handbook — Straight Line
A mathematics problem uses Slope–intercept line. Given x-value (x) = 8.0000; intercept (b) = 9.5000; y-value (y) = 54.4000, determine the slope (m).
Given
Find
slope (m)
Start with the thinking
- The governing relation printed in this handbook section is Slope–intercept line.
- Everything except m is given, so isolate m 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.
- Mathematics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that m stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning m = 5.6125 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 11.2250 — kept a factor of two that cancels in the correct rearrangement.
- 2.8063 — dropped that same factor in the other direction.
- 6.1738 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Mathematics → Straight Line
A drafter verifies a straight line segment on a coordinate layout. Given x1 (x1) = 3.5000; x2 (x2) = 13.5000; y1 (y1) = 5.5000; slope (m) = 3.0500, determine the y2 (y2).
Given
Find
y2 (y2)
Start with the thinking
- The governing relation printed in this handbook section is Straight Line — two-point slope.
- Everything except y2 is given, so isolate y2 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.
- The FE Handbook Straight Line relation gives the slope through two points on a line.
Figure 4 — schematic for Straight Line — two-point slope — solve for y2 — Straight Line (4)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for y2:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning y2 = 36.0000 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 72.0000 — kept a factor of two that cancels in the correct rearrangement.
- 18.0000 — dropped that same factor in the other direction.
- 39.6000 — rounded an intermediate value before the final step.
Reference: FE Handbook — Straight Line
A mathematics problem uses Slope–intercept line. Given slope (m) = 2.0000; x-value (x) = 7.0000; y-value (y) = 38.3000, determine the intercept (b).
Given
Find
intercept (b)
Start with the thinking
- The governing relation printed in this handbook section is Slope–intercept line.
- Everything except b is given, so isolate b 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.
- Mathematics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that b stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning b = 24.3000 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 48.6000 — kept a factor of two that cancels in the correct rearrangement.
- 12.1500 — dropped that same factor in the other direction.
- 26.7300 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Mathematics → Straight Line
A surveyor plots a straight line between two staked points. Given x1 (x1) = 4.5000; y1 (y1) = 7.0000; y2 (y2) = 25.5000; slope (m) = 2.6500, determine the x2 (x2).
Given
Find
x2 (x2)
Start with the thinking
- The governing relation printed in this handbook section is Straight Line — two-point slope.
- Everything except x2 is given, so isolate x2 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.
- The FE Handbook Straight Line relation gives the slope through two points on a line.
Figure 6 — schematic for Straight Line — two-point slope — solve for x2 — Straight Line (6)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for x2:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning x2 = 11.4811 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 22.9623 — kept a factor of two that cancels in the correct rearrangement.
- 5.7406 — dropped that same factor in the other direction.
- 12.6292 — rounded an intermediate value before the final step.
Reference: FE Handbook — Straight Line
A mathematics problem uses Slope–intercept line. Given slope (m) = 4.9000; intercept (b) = -4.0000; y-value (y) = 42.8000, determine the x-value (x).
Given
Find
x-value (x)
Start with the thinking
- The governing relation printed in this handbook section is Slope–intercept line.
- Everything except x is given, so isolate x 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.
- Mathematics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that x stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning x = 9.5510 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 19.1020 — kept a factor of two that cancels in the correct rearrangement.
- 4.7755 — dropped that same factor in the other direction.
- 10.5061 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Mathematics → Straight Line
A designer checks the slope of a straight line on a site grading plan. Given x1 (x1) = 1.5000; x2 (x2) = 11.0000; y1 (y1) = -2.5000; y2 (y2) = 13.0000, determine the slope (m).
Given
Find
slope (m)
Start with the thinking
- The governing relation printed in this handbook section is Straight Line — two-point slope.
- Everything except m is given, so isolate m 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.
- The FE Handbook Straight Line relation gives the slope through two points on a line.
Figure 8 — schematic for Straight Line — two-point slope — solve for slope (case 2) — Straight Line (8)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for m:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning m = 1.6316 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 3.2632 — kept a factor of two that cancels in the correct rearrangement.
- 0.8158 — dropped that same factor in the other direction.
- 1.7947 — rounded an intermediate value before the final step.
Reference: FE Handbook — Straight Line
A mathematics problem uses Slope–intercept line. Given slope (m) = 1.3000; x-value (x) = 9.5000; intercept (b) = -1.5000, determine the y-value (y).
Given
Find
y-value (y)
Start with the thinking
- The governing relation printed in this handbook section is Slope–intercept line.
- Everything except y is given, so isolate y 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.
- Mathematics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that y stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning y = 10.8500 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 21.7000 — kept a factor of two that cancels in the correct rearrangement.
- 5.4250 — dropped that same factor in the other direction.
- 11.9350 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Mathematics → Straight Line
A drafter verifies a straight line segment on a coordinate layout. Given x1 (x1) = 4.0000; x2 (x2) = 10.5000; y1 (y1) = 9.5000; slope (m) = 1.4000, determine the y2 (y2).
Given
Find
y2 (y2)
Start with the thinking
- The governing relation printed in this handbook section is Straight Line — two-point slope.
- Everything except y2 is given, so isolate y2 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.
- The FE Handbook Straight Line relation gives the slope through two points on a line.
Figure 10 — schematic for Straight Line — two-point slope — solve for y2 (case 2) — Straight Line (10)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for y2:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning y2 = 18.6000 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 37.2000 — kept a factor of two that cancels in the correct rearrangement.
- 9.3000 — dropped that same factor in the other direction.
- 20.4600 — rounded an intermediate value before the final step.
Reference: FE Handbook — Straight Line