搜搜做题作业网必修四A22
来源：学生作业帮 编辑：搜搜做题作业网作业帮 分类：数学作业 时间：2024/04/30 04:28:43
解题思路： 三角函数
解题过程：
解：0<β<π/4<α<3π/4,cos(π/4-α)=3/5,sin(3π/4+β)=5/13，
-π/2<π/4-α<0 3π/4<3π/4+β<π
cos(3π/4+β)=-12/13 sin((π/4-α)=-4/5
sin(α+β)=sin[(3π/4+β)-(π/4-α)-π/2]=-cos[(3π/4+β)-(π/4-α)]
=-cos(π/4-α)*cos(3π/4+β)*-sin(3π/4+β)sin(π/4-α)
=-3/5*(-12/13)-5/13*(-4/5)
=56/65
最终答案：略
解题过程：
解：0<β<π/4<α<3π/4,cos(π/4-α)=3/5,sin(3π/4+β)=5/13，
-π/2<π/4-α<0 3π/4<3π/4+β<π
cos(3π/4+β)=-12/13 sin((π/4-α)=-4/5
sin(α+β)=sin[(3π/4+β)-(π/4-α)-π/2]=-cos[(3π/4+β)-(π/4-α)]
=-cos(π/4-α)*cos(3π/4+β)*-sin(3π/4+β)sin(π/4-α)
=-3/5*(-12/13)-5/13*(-4/5)
=56/65
最终答案：略