"to convert from "color(blue)"cartesian to polar"to convert from cartesian to polar
"that is "(x,y)to(r,theta)" where"that is (x,y)→(r,θ) where
•color(white)(x)r=sqrt(x^2+y^2)∙xr=√x2+y2
•color(white)(x)theta=tan^-1(y/x);-pi< theta<= pi∙xθ=tan−1(yx);−π<θ≤π
"here "x=-3" and y=3here x=−3andy=3
rArrr=sqrt((-3)^2+3^2)=sqrt18=3sqrt2⇒r=√(−3)2+32=√18=3√2
(-3,3)" is in the second quadrant so "theta" must be in the "(−3,3) is in the second quadrant so θ must be in the
"second quadrant"second quadrant
theta=tan^-1(1)=pi/4larrcolor(red)"related acute angle"θ=tan−1(1)=π4←related acute angle
rArrtheta=pi-pi/4=(3pi)/4larrcolor(red)"in second quadrant"⇒θ=π−π4=3π4←in second quadrant
rArr(-3,3)to(3sqrt2,(3pi)/4)⇒(−3,3)→(3√2,3π4)