Question

if x=a Sin theta+b cos theta and y=a Cos theta-b Sin theta.Find x2+y2

Answer 1

x²+y²
(a sin theta+ b cos theta)² + (a cos theta+ b sin theta)²
=(a²sin²theta+b²cos²theata+ab sin theta cos theta )+(a²cos²theta+b²sin²theta-ab sin theta cos theta) using (a+b)²=a²+b²+2ab,(a-b)²=a²+b²-2ab
=a²(sin²theta+cos²theta)+b²(sin²theta + cos²theata)
=a²+b²(sin²theta+cos²theta=1)

Answer 2

ANSWER is here...hope this help you buddy....