Slope in Geometry Math Example 1

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Example 1

easy
Find the slope of the line through A(โˆ’2,5)A(-2, 5) and B(4,โˆ’1)B(4, -1). Describe what the slope tells us about the line's direction.

Solution

  1. 1
    Step 1: Apply the slope formula: m=y2โˆ’y1x2โˆ’x1=โˆ’1โˆ’54โˆ’(โˆ’2)=โˆ’66=โˆ’1m = \dfrac{y_2 - y_1}{x_2 - x_1} = \dfrac{-1 - 5}{4 - (-2)} = \dfrac{-6}{6} = -1.
  2. 2
    Step 2: A slope of โˆ’1-1 means the line falls 11 unit for every 11 unit moved to the right.
  3. 3
    Step 3: The line makes a 45ยฐ45ยฐ angle below horizontal (since โˆฃmโˆฃ=1|m|=1 and the slope is negative, it descends left-to-right).

Answer

m=โˆ’1m = -1; the line descends at 45ยฐ45ยฐ from left to right.
Slope measures steepness and direction: positive slope rises left-to-right, negative slope falls, zero is horizontal, undefined is vertical. A slope of โˆ’1-1 means a 45ยฐ45ยฐ downward inclination, a special case where the line is perpendicular to slope +1+1 lines.

About Slope in Geometry

The steepness of a line expressed as rise over run, connecting the algebraic slope formula to the geometric angle of inclination.

Learn more about Slope in Geometry โ†’

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