(T3 - T5) = sin^3A + cos^3A -sin^5A - cos^5A
= sin^3A - sin^5A + cos^3A - cos^5A
= sin^3A( 1 - sin^2A) + cos^3A ( 1- cos^2A)
= sin^3A*cos^2A + cos^3A*sin^2A
= sin^2A*cos^2A(sinA + cosA)
If you divide this by T1 you get sin^2A*cos^2A.
Proceed in the same manner in right hand side.