2sin²（π/4+B/2）=1-cos（π/2+B）如何推导

2sin²（π/4+B/2）=1-cos（π/2+B）如何推导
2sin²（π/4+B/2）=1-cos（π/2+B）如何推导

2sin²（π/4+B/2）=1-cos（π/2+B）如何推导
利用二倍角公式cos2A=1-2sin²A的变形公式：2sin²A=1-cos2A
令A=π/4+B/2
即得：2sin²(π/4+B/2)=1-cos(π/2+B)