Question

Tính giá trị biểu thức sau:

\(\sin15^0+\sin75^0-\cos15^0-\cos75^0+\sin30^0\)

Answer 1

\(sin15^o+sin75^o-cos15^o-cos75^o+sin30^o\)

\(=\left(sin15+sin75^o\right)-\left(cos15^o+cos75^o\right)+sin30^o\)

\(=\dfrac{\sqrt{6}}{2}-\dfrac{\sqrt{6}}{2}+\dfrac{1}{2}\)

\(=0+\dfrac{1}{2}\)

\(=\dfrac{1}{2}\)

Answer 2

\(sin15^o+sin75^o-cos15^0-cos75^o+sin30^o\)

\(=cos75^o+cos15^0-cos15^0-cos75^o+sin30^o\)

\(=sin30^o=\dfrac{1}{2}\)