It is known that SiNx + cosx = - 1 / 5 (135 °)

It is known that SiNx + cosx = - 1 / 5 (135 °)

Here we can easily get SiNx = 3 / 5, cosx = - 4 / 5
sin2x=2sinxcosx=-24/25
cos2x=1-2sinx^2=7/25
cos3x=cos(2x+x)=cos2xcosx-sin2xsinx=44/125
sin3x=sin(2x+x)=sin2xcosx+sinxcos2x=117/125
So:
(6 / 5) / (- 7 / 5-44 / 125 + 117 / 125) = I am powerless I don't want to count!
You can do it yourself, master. Mathematics is still up to you