Answer:
The angle corresponding to angle 4 is angle 8
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.
The number 8 is a multiple of 16, 2 x 8 = 16 . And the number 8 + 10 = 18
So, I would think it's 8.
Hope I was able to help you. :-)