化简计算cos(80°+3α)cos(35°+α)+sin(80°+α)cos(55°-α)的过程?没有打错，是3α^.^

分类: 作业答案 • 2021-12-19 15:55:08

问题描述：

化简计算cos(80°+3α)cos(35°+α)+sin(80°+α)cos(55°-α)的过程?
没有打错，是3α
^.^

答

cos(80°+α)cos(35°+α)+sin(80°+α)cos(55°-α)
=cos(80°+α)cos(35°+α)+sin(80°+α)sin(35°+α)
=cos[(80°+α)-(35°+α)]
=cos55°
cos(80°+3α)?