Question

[2/(2-cos y)]'为什么用公式做出来是(-2sin y *y')/(2-cos)的平方呢

Answer 1

2/(2-cosy)=2*(2-cosy)^(-1)

所以导数=2*[(-1)*(2-cosy)^(-1-1)*(2-cosy)']

=-2*(2-cosy)^(-2)*(siny*y')

=-2siny*y'/(2-cosy)^2