The Cartesian equivalent of the polar coordinates (r, theta) is
(r cos t, r sin t), where t = theta.
So, (2, 3pi/4) becomes
(2 cos(3pi/4), 2 sin(3pi/4))
(2 • -sqrt{2}/2, 2 • sqrt{2}/2)
Answer: (-sqrt{2}, sqrt{2})
Done.
Note: sqrt = square root for short.
