Question

(cos theta + i sin theta)^2​

Answer 1

Answer:

(cos theta + i sin theta)²

= cos²theta + 2cos theta .sin theta + i²sin²theta

..............[since, (a+b)²=a²+2ab +b²]

= cos²theta + 2sin theta. cos theta -sin²theta

..........[ since, i²=-1]

= cos²theta -sin²theta + 2sin theta.cos theta

= cos2 theta +2 sin theta.cos theta

........[since, cos²x - sin²x = cos2x]