Hello ppl. I have a problem in finding out the volume of solid formed by the revolution of one loop of lemniscate of bernoulli ( r²=a²cos2θ) about the initial line θ =0 Using the relevant forumula for the volume of the solid generated by the revolution of one loop of the polar curve about the initial line, http://img357.imageshack.us/img357/4228/93696380jt5.jpg [Broken] , where V is the volume of the solid and π/4 and 0 are the upper and lower limits respectively. In this problem , http://img88.imageshack.us/img88/6624/19344682ul0.jpg [Broken] But i am not able to integrate further. I am kinda stuck here. What substitution should i take?Please help me.