Question

show that (costheta+isintheta)^3 = cos3theta+isin3theta

Answer 1

Answer:

we know e^itheta=costheta+i sin theta

therefore (costheta + i sin theta) =( e^itheta)^3

and (e^itheta)^3= cos3theta+ i sin3 theta

Step-by-step explanation:

this by De morvies theorm Eulers formula