Question

Prove that if x= a sin + b cos and y = a cos - b sin , then
x²+ y² = a ²+ b²​

Answer 1

Answer:

a²+b²

Step-by-step explanation:

(asin+bcos)²+(acos-bsin)²

a²sin²+b²cos²+2absincos+a²cos²+b²sin²-2absincos

a²(sin²+cos²)+b²(sin²+cos²)=a²+b²