Question

tan(a+b)=m,tan(a_b)=n,tan2a=?

Answer 1

tan 2A = tan ( (A + B) + (A -B) ) = ( tan ( A+ B ) + tan (A - B))  / 1 -   tan ( A+ B ) tan (A - B) = (m + n) / 1 - mn 

hope it helps u dear