SOLUTION: These kind of problems are really confusing to me... simplify 5cis115degrees * 4cis10degrees I'm not even sure where to start. thank you much!

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Question 173152: These kind of problems are really confusing to me...
simplify
5cis115degrees * 4cis10degrees
I'm not even sure where to start.
thank you much!
Answer by jim_thompson5910(35256) (Show Source):
You can put this solution on YOUR website!
In general cis(x) = cos(x)+i*sin(x) where . The "cis" is just a faster way of writing the right side of the equation

So

cis(115) = cos(115)+i*sin(115)

Use a calculator to get:

cos(115) = -0.42262 and sin(115) = 0.90631

So this means that

cis(115) = -0.42262 + 0.90631*i

Furthermore, 5*cis(115) = 5*(-0.42262 + 0.90631*i)=-2.1131+4.53155*i

I hope I got you going in the right direction to evaluate 4*cis(10)

If not, then either let me know or repost the problem