Bài 1:
Ta có: \(A=\sin^6\alpha+3\cdot\sin^2\alpha\cdot\cos^2\alpha+\cos^6\alpha\)
\(=\left(\sin^2\alpha+\cos^2\alpha\right)^3-3\cdot\sin^2\alpha\cdot\cos\alpha\cdot\left(\sin^2\alpha+\cos^2\alpha\right)+3\cdot\sin^2\alpha\cdot\cos^2\alpha\)
\(=1^3\)
=1