Question 173152
In general cis(x) = cos(x)+i*sin(x) where {{{i=sqrt(-1)}}}. 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