Concepts and Vocabulary
True or False To find \(\int \cos ^{5}x\,dx,\) factor out \(\cos x\) and use the identity \(\cos ^{2}x=1-\sin ^{2}x.\)
True or False To find \(\int \sin (2x) \cos (3x) \,dx,\) use a product-to-sum identity.
Skill Building
In Problems 3–10, find each integral.
\(\int \cos ^{5}x\,dx\)
\(\int \sin ^{3}x\,dx\)
\(\int \sin ^{6}x\,dx\)
\(\int \cos ^{4}x\,dx\)
\(\int \sin ^{2}\left( \pi x\right) \,dx\)
\(\int \cos ^{4}(2x) \,dx\)
\(\int_{0}^{\pi }\cos ^{5}x~dx\)
\(\int_{-\pi /3}^{\pi /3}\sin ^{3}x\,dx\)
In Problems 11–18, find each integral.
\(\int \sin ^{3}x\cos ^{2}x\,dx\)
\(\int \sin ^{4}x\cos ^{3}x\,dx\)
\(\int \sin ^{2}x\cos ^{2}x\,dx\)
\(\int \sin ^{4}x\cos ^{2}x\,dx\)
\(\int \sin x\cos ^{1/3}x\,dx\)
\(\int \cos ^{3}x\sin ^{1/2}x\,dx\)
\(\int \sin ^{2}\left(\dfrac{x}{2}\right) \cos ^{3}\left( \dfrac{x}{2}\right) \,dx\)
\(\int \sin ^{3}(4x) \cos ^{3}(4x) \,dx \)
In Problems 19–26, find each integral.
\(\int \tan ^{3}x\sec ^{2}x\,dx\)
\(\int \tan x\sec ^{5}x\,dx\)
\(\int \tan ^{2}x\sec ^{2}x\,dx\)
\(\int \tan ^{5}x\sec ^{2}x\,dx\)
\(\int \tan ^{2}x\sec ^{3}x\,dx\)
\(\int \tan ^{4}x\,\sec x\,dx\)
\(\int \cot ^{3}x\csc x\,dx\)
\(\int \cot ^{3}x\csc ^{2}x\,dx\)
In Problems 27–34, find each integral.
\(\int \sin (3x) \cos x\,dx\)
\(\int \sin x\cos (3x) \,dx\)
\(\int \cos x\cos (3x) \,dx\)
\(\int \cos (2x) \cos x\,dx \)
\(\int \sin (2x) \sin (4x) \,dx\)
\(\int \sin (3x) \sin x\, dx\)
\(\int_{0}^{\pi /2}\sin (2x) \sin x\,dx\)
\(\int_{0}^{\pi }\cos x\cos (4x) \,dx\)
In Problems 35–56, find each integral.
\(\int \sin ^{2}x\cos x\,dx\)
\(\int \sin ^{3}x\cos x\,dx\)
\(\int \dfrac{\sin x\,dx}{\cos ^{2}x}\)
\(\int \dfrac{\cos x\,dx}{\sin ^{4}x}\)
\(\int \cos ^{3}(3x) \,dx\)
\(\int \sin ^{5}(3x) \,dx\)
\(\int_{0}^{\pi }\sin ^{3}x\cos ^{5}x\,dx\)
\(\int_{0}^{\pi /2}\sin ^{3}x\cos ^{3}x\,dx\)
\(\int \tan ^{3}x\,dx\)
\(\int \cot ^{5}x\,dx\)
\(\int \dfrac{\sec ^{6}x}{\tan ^{3}x}\,dx\)
\(\int \tan ^{1/2}x\sec ^{2}x\,dx\)
\(\int \csc ^{2}x\cot ^{5}x\,dx\)
\(\int \cot x\csc ^{2}x\,dx\)
487
\(\int \cot(2x) \csc^{4}(2x)~dx\)
\(\int \cot^{2}(2x) \csc^{3}(2x)dx\)
\(\int_{0}^{\pi /4}\tan^{4}x\sec^{3}xdx \)
\(\int_{0}^{\pi /4}\tan^{2}x\sec xdx\)
\(\int \sin \left( \dfrac{x}{2}\right) \cos \left( \dfrac{3x}{2}\right)dx\)
\(\int \cos (-x) \sin (4x)dx\)
\(\int \sin \left( \dfrac{x}{2}\right) \sin \left( \dfrac{3x}{2}\right)dx\)
\(\int \cos (\pi x) \cos ( 3\pi x)dx\)
Applications and Extensions
Volume of a Solid of Revolution Find the volume of the solid of revolution generated by revolving the region bounded by the graph of \(y=\sin x\) and the \(x\)-axis from \(x=0\) to \(x=\pi \) about the \(x\)-axis. See the figure below.
Volume of a Solid of Revolution Find the volume of the solid of revolution generated by revolving the region bounded by the graphs of \(y=\cos x\), \(y=\sin x\), and \(x=0\) from \(x=0\) to \(x=\dfrac{\pi }{4}\) about the \(x\)-axis.
Average Value
Rectilinear Motion The acceleration \(a\) of an object at time \(t\) is given by \(a(t) =\cos ^{2}t\sin t\) m\(/\)s\(^{2}\). At \(t=0\), the object is at the origin and its speed is 5m\(/\)s. Find its distance from the origin at any time \(t\).
Area and Volume Let \(A\) be the area of the region in the first quadrant bounded by the graphs of \(y=\sec x\), \(y=2\sin x\), and the \(y\)-axis.
Find \(\int \sin ^{4}x\,dx\).
Derive a formula for \(\int \sin (mx) \sin (nx) \,dx,\quad m ≠ n\).
Derive a formula for \(\int \sin (mx) \cos (nx) \,dx,\quad m ≠ n\).
Derive a formula for \(\int \cos (mx) \cos (nx) \,dx,\quad m ≠ n\).
Challenge Problems
Use the substitution \(\sqrt{x}\,=\,\sin y\) to find \(\int_{0}^{1/2}\dfrac{\sqrt{x}}{\sqrt{1-x}}\,dx\). \(\bigg(\)Hint: sin\(^{2}y\,{=}\,\dfrac{1\,{-}\,\cos (2y)}{2}.\bigg)\)
Use an appropriate substitution to show that \[ \int_{0}^{\pi /2}\sin ^{n}\theta \,d\theta =\,\int_{0}^{\pi /2}\cos ^{n}\theta \,d\theta . \]