Use an identity to rewrite each squared trigonometric function as a sum of standard integrable terms.
Squared sine and cosine
| Integral | Identity and rewrite | Antiderivative |
|---|---|---|
| \(\displaystyle\int\sin^2x\,\mathrm{d}x\) | \(\sin^2x=\dfrac{1-\cos2x}{2}\) | \(\dfrac{x}{2}-\dfrac{\sin2x}{4}+C\) |
| \(\displaystyle\int\cos^2x\,\mathrm{d}x\) | \(\cos^2x=\dfrac{1+\cos2x}{2}\) | \(\dfrac{x}{2}+\dfrac{\sin2x}{4}+C\) |
Squared tangent and cotangent
| Integral | Identity and rewrite | Antiderivative |
|---|---|---|
| \(\displaystyle\int\tan^2x\,\mathrm{d}x\) | \(\tan^2x=\sec^2x-1\) | \(\tan x-x+C\) |
| \(\displaystyle\int\cot^2x\,\mathrm{d}x\) | \(\cot^2x=\mathrm{cosec}^2x-1\) | \(-\cot x-x+C\) |
\[\cos2A=1-2\sin^2A=2\cos^2A-1\]
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