if m power of Sin x is odd, put Cos x = t .
If n power of Cos x is odd, put Sin x = t.
If both m, and n are odd then put Sin x = t or Cos x = t.
If both m, and n are even then See the sum of power = (m + n).
( a ) if (m + n ) = +ive even Integer then convert trigonometric equation in linear form and integrate it.
( b ) if (m + n ) = -ive even Integer then put Tan x = t and integrate it.