Question

triangle PQR is right angled at P. The points P(2;6), Q(-1;2) and R(6;k)

Determine K

Answer 1

helps to draw a general setup to get the juices flowing

Answer 2

id "move" P to the origin (2-2,6-6) = (0,0) and the others move in kind

Q=(-1-2,2-6) = (-3,-4)

R=(6-2,k-6) = (4,k')

Answer 3

can you find the slope from the P to Q now?

Answer 4

Yeah i have worked out the gradient it's 4 and since it's perpendicular the gradient of PR is -1/4 so thats where i'm stuck

Answer 5

another method if youknow what a dot product is might be simpler ....