为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2
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![为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2](/uploads/image/z/3689843-59-3.jpg?t=%E4%B8%BA%E4%BB%80%E4%B9%88sina%2Bsinb%3D%3D2sin%28a%2Bb%29%2F2%2Acos%28a-b%29%2F2)
为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2
为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2
为什么sina+sinb==2sin(a+b)/2*cos(a-b)/2
sina+sinb
=sin[(a+b)/2+(a-b)/2]+sin[(a+b)/2-(a-b)/2]=2sin(a+b)/2*cos(a-b)/2