Integrating Powers of Cotangents and Cosecants

You can integrate powers of cotangents and cosecants similar to the way you do tangents and secant. For example, here’s how to integrate cot8 x csc6 x:

  1. Peel off a csc2 x and place it next to the dx:

    image0.png
  2. Use the trig identity 1 + cot2 x = csc2 x to express the remaining cosecant factors in terms of cotangents:

    image1.png
  3. Use the variable substitution u = cot x and du = –csc2 x dx:

    image2.png

At this point, the integral is a polynomial, and you can evaluate it.

Sometimes, knowing how to integrate cotangents and cosecants can be useful for integrating negative powers of other trig functions — that is, powers of trig functions in the denominator of a fraction.

For example, suppose that you want to integrate

image3.png

You can use trig identities to express it as cotangents and cosecants:

image4.png
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