Question

PLEASE HELP!!

Find the rectangular coordinates of the point with the polar coordinates [7, 2π/3]

1) [-7/2, 7√3/2]
2) [-7/2, 7/2]
3) [7/2, -7/2]
4) [7√3/2, -7/2]

Answer 1

\[\Large\rm (r,\theta)=\left(7,\frac{2\pi}{3}\right)\]

\[\Large\rm x=r \cos \theta,\qquad\qquad y=r \sin \theta\]

Answer 2

\[\Large\rm x=7\cos\frac{2\pi}{3}\]Remember your special angles and the unit circle and all that?

Answer 3

A little bit.