How do you find the angle between the lines 3x+4y=12 and 4x-3y=12?

1 Answer
May 17, 2018

90^@

Explanation:

Rearrange so 3x+4y=12 =>4y=-3x+12=>y=-3/4x+3

4x-3y=12=>-3y=-4x+12=>y=4/3x-4

the two gradients are -3/4 and 4/3

-3/4xx4/3=-12/12=-1

so they are perpendicular.