what do i do

[north dome]

id say first thing u do is work out the gradient of PQ

then find the negative reciprocal for the perpendicula gradient

then u work out the mid point of PQ and substitute the coordinates into the equation y-y1 = m(x-x1) with m = the gradient for the perpendicular line (negative reciprocal) and y1 and x1 being the midpoint coordinates

then in the end u just move everything to the left so it all equals 0