sin(a-派/4)=7根号2/10且派/2

问题描述:

sin(a-派/4)=7根号2/10且派/2

sin(a-π/4)=7√2/10 cos(a-4/π)=√2/10 sin(2a-2/π)=2sin(a-π/4)cos(a-4/π)=7/25
cos2a=-7/25 sin2a=-24/25 tan2a=24/7 tan(2a+4/π)=(tan2a+1)/(tan2a-1)=31/17