Question

Tính

A=\(sin^4\alpha+cos^4\alpha+2sin^2\alpha.cos^2\alpha\)

B=\(\left(sin^2\alpha-cos^2\alpha\right)^2+2sin^2\alpha.cos^2\alpha\)

C=\(sin^6\alpha+cos^6\alpha+3sin^2\alpha.cos^2\alpha\)

Answer 1

 \(A=\left(sin^2\alpha+cos^2\alpha\right)^2=1\)

 

Answer 2

b: \(B=\left(sin^2a+cos^2a\right)^2-2sin^2acos^2a\)

\(=1-2\cdot sin^2a\cdot cos^2a\)

c: \(=\left(sin^2a+cos^2a\right)^3-3\cdot sin^2a\cdot cos^2a\cdot\left(sin^2a+cos^2a\right)+3sin^2a\cdot cos^2a\)

=1