已知sin(派/4)+x=-1/5,求cos(3/4派)+x的值_数学解答

已知sin(派/4)+x=-1/5,求cos(3/4派)+x的值

人气：482 ℃　时间：2020-09-30 21:46:08

解答

cos[(3/4派)+x]
=cos[π-(π/4-x)]
=-cos(π/4-x)
=-cos[(π/2-(π/4+x)]
=-sin(π/4+x)
=1/5