Quiz 6:複角公式
\(\cos {65^ \circ }\sin {110^ \circ } + \cos {25^ \circ }\sin {20^ \circ }\) 之值為
\(\frac{{\sqrt 2 }}{2}\)
\(\frac{{\sqrt 3 }}{2}\)
\(\quad \frac{1}{2}\)
\( - \frac{{\sqrt 3 }}{2}\)