Volume of Revolution to a Parametric Curve : Edexcel Core Maths C4 June 2011 Q7(c) : ExamSolutions

[Snakebloke]

Phew that was a fairly tough question in my eyes, thank you for explaining it so clearly and methodically.

[AfroTwine]

Hello, thank you very much for all of your videos. I have a question regarding this video; as you are integrating tan^2(theta), why can you not use the "inverse chain rule", by putting tan^2(theta) = (tan(theta))^2 (I know the question wants it in two terms, but it doesn't work anyway)? Thanks in advance.

[Pnygup]

can I use pi intergrate 1/2(1-cos2θ)? but the answer was different.

[bobbbbbby]

don't know whether you'll see this, but for the question i went down the route of finding the cartesian equation which seemed nice because it comes out as y^2=x^2/1+x^2 which works out well for the intregral of πy^2. Problem is I was then unsure as to what method to use to integrate the above equation. Using a calculator I get the correct value for the integral so i works i just don't know how to integrate for the exact value.
I know this method is more awkward but I was just wondering whether there is a way of doing it using c4 maths or would I just need to stick with the method you've detailed.
Any help would be much appreciated

[KesterBates]

why can't you integrate the cartesian equation since that's already y in terms of x?