Question

Tính

\(A=sin^212^o+sin^270^o-sin^235^o+sin^230^o+sin^278^o-sin^255^o+sin^220^o\)

Answer 1

\(=\left(\sin^212^0+\sin^278^0\right)+\left(\sin^270^0+\sin^220^0\right)-\left(\sin^235^0+\sin^255^0\right)+\sin^230^0\)

\(=1+1-1+\dfrac{1}{4}=1+\dfrac{1}{4}=\dfrac{5}{4}\)