The number cis 75 + cis 83 + cis91 +...+ cis 147 is expressed in the form r cis(theta), where 0 <= theta < 360.

Question

Find theta in degrees.

@Damon I didn't understand your reply to my post. Could you please explain it to me?

Answer 1

see the previous post with Damon's response.

calculate a above.
calculate b above.

theta= arctan (b/a)

Answer 2

http://www.jiskha.com/display.cgi?id=1408819018

Answer 3

How do I calculate a and b?

Answer 4

Use your calculator
cos 75 =
cos 83 =
cos 91 =
cos 99 =
cos 107 =
cos 115 =
cos 123 =
cos 131 =
cos 139 -
cos 147 =
now add to get a :)

Answer 5

bruh you can't use a calculator for these problems that defeats the purpose