cos(45+30)cos(45-30)+sin(45+30)sin(45-30=)_数学解答

cos(45+30)cos(45-30)+sin(45+30)sin(45-30=)

人气：493 ℃　时间：2020-08-31 08:29:45

解答

cos(45+30)cos(45-30)+sin(45+30)sin(45-30)
=cos[(45+30)-(45-30)]
=cos(75-15)
=cos60
=1/2