Gievn that tan A =3 and sin (A-B)=2 cos (A+B) , find tan B
i got tan B=-1/5
Find general solution , in rad cos b + cos 3b +cos 5b =0
cos b + 2 cos 4b cos b =0
cos b (1+2cos 4b )=0
cos b =0
and cos b = -1/2
I can only reach this far , i am not sure about the general solution >
Deduce $\displaystyle \cos^2 b+\cos^2 3b+\cos^2 5b=\frac{3}{2}$
no idea bout this .