Question

[Đăng Khoa Nguyễn]

Chứng minh: \(\sin^4x+\cos^2x\cdot\sin^2x+\sin^2x=2\sin^2x\)

Answer 1

[Hồng Phúc]

\(sin^4x+cos^2x.sin^2x+sin^2x\)

\(=sin^2x.\left(sin^2x+cos^2x\right)+sin^2x\)

\(=sin^2x+sin^2x\)

\(=2sin^2x\)