prove that (cos theta + i sin theta) ^ 3
cos 3theta + i sin 3 theta
by expanding the whole cube
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Well, have you tried expanding the cube?
yeah i did........ actually we had to it for square and cube, i did for the square but for the cube i can not derive this, i can not prove it using x^3 + y^3 + 3xy^2 + 3yx^2
so kindly prove it for me
I'll do no such thing, you'll prove it yourself. Start by substituting "cos(theta)" for x and " i sin(theta) " for y. Simplify and collect your real parts and imaginary parts.
thanks man, ibdutt, thanks a lot
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