Q3
Let
I=?root(sin2xcos2x)
multiply and divide by root(2)
I = ?root(sin4x)/root(2)
Let
I1 = ?root(sin4x) dx
Put sin4x=t2
4cos4xdx=2tdt
dx=tdt/2root(1-t2)
I1 = ?t2dt/2root(1-t2)
I1 = (1/2) ? t2dt/root(1-t2)
NOw add and subtract by 1 in numerator
rest is easy
? is integral sign
Q2
? tan^4x
?tan^2xtan^2x
?(sec^2x-1)tan^2x
?sec^2xtan^2x - ?tan^2x
put tanx=t - ?sec^2x-1
?t^2dt - tanx -x
t^3/3 - tanx-x +C
tan^3x/3 - tanx-x+C