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

Tính

A=\(\dfrac{sin\alpha75^o}{2cos15^o}\)

B=\(sin^210^o+sin^220^o+sin^230^o+...+sin^280^o\)

C=\(4tan62^o-3cot28^o\)

Cho cotα=\(\dfrac{8}{15}\)Tính M=\(\dfrac{sin\alpha+3cos\alpha}{4cos\alpha-3sin\alpha}\)

cho cotα=\(\dfrac{3}{4}\) Tính sinα,cosα,tanα