LINES AND ANGLES
74 . Using an Equation to Find the Slope
To find the slope of a line from an equation, put the equation into the slope-intercept form:
y = mx + b
The slope is m. To find the slope of the equation 3 x + 2y = 4, rearrange it:
The slope is
75 . Using an Equation to Find an Intercept
To find the y-intercept, you can either put the equation into y = mx + b (slope-intercept) form
—in which case b is the y-intercept—or you can just plug x = 0 into the equation and solve for
y. To find the x-intercept, plug y = 0 into the equation and solve for x.
76 . Finding the Midpoint
The midpoint of two points on a line segment is the average of the x-coordinates of the
endpoints and the average of the y-coordinates of the endpoints. If the endpoints are (x 1 ,y 1 )
and (x 2 ,y 2 ), the midpoint is The midpoint of (3,5) and (9,1) is (or
(6, 3).
77 . Intersecting Lines
When two lines intersect, adjacent angles are supplementary, and vertical angles are equal.
