(a)[4]
By using the substitution $u = \cos x$, show that $\int_{0}^{\pi} \sin 2x\, e^{2\cos x}\, dx = \int_{-1}^{1} 2u e^{2u}\, du$.
(b)[4]
Hence determine the exact value of $\int_0^\pi \sin 2x\, e^{2\cos x}\, dx$.
Mathematics 9709 · AS & A Level · Integration
By using the substitution $u = \cos x$, show that $\int_{0}^{\pi} \sin 2x\, e^{2\cos x}\, dx = \int_{-1}^{1} 2u e^{2u}\, du$.
Hence determine the exact value of $\int_0^\pi \sin 2x\, e^{2\cos x}\, dx$.