Marc L. answered 11/24/20
Tutor
New to Wyzant
Helping others understand things one step at a time
x2+y2=r2
x=rcos(θ)
y=rsin(θ)
knowing this let's plug in
r4=2(rcos(θ))(rsin(θ)), r4=2r2cos(θ)sin(θ), r2=2cos(θ)sin(θ), r2=sin(2θ)