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Exercise 11

Avg difficulty 2.5

This problem centers on finding antiderivatives for the basic trigonometric functions other than sin⁡(x)\sin(x) and cos⁡(x)\cos(x).

  1. Consider the indefinite integral ∫tan⁡(x) dx\int \tan(x) \, dx. By rewriting the integrand as tan⁡(x)=sin⁡(x)cos⁡(x)\tan(x) = \frac{\sin(x)}{\cos(x)} and identifying an appropriate function-derivative pair, make a uu-substitution and hence evaluate ∫tan⁡(x) dx\int \tan(x) \, dx.

  2. In a similar way, evaluate ∫cot⁡(x) dx\int \cot(x) \, dx.

  3. Consider the indefinite integral ∫sec⁡2(x)+sec⁡(x)tan⁡(x)sec⁡(x)+tan⁡(x) dx\begin{gathered} \int \frac{\sec^2(x) + \sec(x) \tan(x)}{\sec(x) + \tan(x)} \, dx \end{gathered}. Evaluate this integral using the substitution u=sec⁡(x)+tan⁡(x)u = \sec(x) + \tan(x).

  4. Simplify the integrand in (c) by factoring the numerator. What is a far simpler way to write the integrand?

  5. Combine your work in (c) and (d) to determine ∫sec⁡(x) dx\int \sec(x) \, dx.

  6. Using (c)-(e) as a guide, evaluate ∫csc⁡(x) dx\int \csc(x) \, dx.

Boelkins, Active Calculus, §5.3 Integration by substitution, Exercise 11

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Adapted from Active Calculus © 2012–2025 Matthew Boelkins. Licensed under CC BY-SA 4.0. Source: Active Calculus. Imported at revision dc86ba3.