amp;∫sin3xcos3xsin(x−θ)sin23x+cos23xdxamp;I=∫sin3xcos3x(sinxcosθ−cosxsinθ)sin23x+cos23xdxamp;=∫sin23xcos2xtanxcosθ−sinθsin23xdx+∫sin2xcos23xcosθ−cotxsinθcos23xdx=amp;∫tanxcosθ−sinθsec2xdx+∫cosθ−cotxsinθcosec2xdxamp;
I=I1+I2 ...... {Let}
For I1 , let tanxcosθ−sinθ=t2
sec2xdx=cosθ2tdt
For I2 , let cosθ−cotxsinθ=z2
cosec2xdx=sinθ2zdz
amp;I=I1+I2amp;=∫cosθt2tdt+∫sinθz2zdzamp;=cosθ2t+sinθ2zamp;=2secθtanxcosθ−sinθ+2cosecθcosθ−cotxsinθamp; Comparing amp;AB=8cosec2θ