(i)[4]
Prove that the identity $\tan 2\theta - \tan \theta \equiv \tan \theta \sec 2\theta$ holds.
(ii)[4]
Hence show that $\displaystyle \int_0^{\frac{\pi}{6}} \tan \theta \sec 2\theta\, d\theta$ equals $\frac{1}{2} \ln \frac{3}{2}$.
Mathematics 9709 · AS & A Level · Integration
Prove that the identity $\tan 2\theta - \tan \theta \equiv \tan \theta \sec 2\theta$ holds.
Hence show that $\displaystyle \int_0^{\frac{\pi}{6}} \tan \theta \sec 2\theta\, d\theta$ equals $\frac{1}{2} \ln \frac{3}{2}$.
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Apply the tan 2A formula to write the LHS in terms of $\tan\theta$” …