Question

Verify each identity:
sin^4x - cos^4x =sin^2x - cos^2x

Answer 1

Step-by-step explanation:

LHS = sin⁴x - cos⁴x

= (sin²x)² - (cos²x)²

= ( sin²x + cos²x ) ( sin²x - cos²x)

[ Using a+b)(a-b)=a2-b2 ]

= 1(sin²x - cos²x)

= sin²x - cos²x = RHS

Hence Proved