Question

If n is an integer, prove that,

(i)cos((n)×(pi) +(theta)) = (-1)^n (cos(theta))​

Answer 1

Step-by-step explanation:

$\cos(n\pi + \alpha ) = ( - 1) {}^{n} \cos( \alpha )$

Ans:

because the value of cos \alpha varies with qurdant

when n is even it gives positive value and when we taken n odd its gives negative value ad qurdant varried value affected.