Question

If you multiply the slopes of two perpendicular lines, what is the result?

2) If line A contains the points (3, -4) and (6, -2), and line B contains the points (-1, 5) and (1, 2), prove that the lines are perpendicular by multiplying their slopes.

3) Line A and line B are perpendicular. Line A contains the points (4,2) and (-1, 3). If one of the points on line B is (3, 7), find another point on line B.
(I got number 2 however dont know how to do 3)Please explain!!!

Answer 1

Find the gradient/slope of Line A:

(3-2)÷(-1-4)

=-0.2

Therefore, the gradient/slope of line B is 5

Using the equation y-y1=m(x-x1) we can find the equation of line B

y-7=5(x-3)

y= 5x-8

Sub in a random value for y (eg. y=2)

2=5x-8

5x=10

X=2

so (2,2)