方法一:f(x) = (sinx)(cosx)f(-x) = sin(-x) * cos(-x) = -sinx * cosx = -f(x),奇函数方法二:f(x) = (sinx)(cosx) = 0.5sin(2x)f(-x) = 0.5sin(-2x) = -0.5sin(2x) = -f(x),奇函数