diff --git a/education/math/MATH1220 (calc II)/Integration with Trig Identities.md b/education/math/MATH1220 (calc II)/Integration with Trig Identities.md index d89668e..5423e06 100644 --- a/education/math/MATH1220 (calc II)/Integration with Trig Identities.md +++ b/education/math/MATH1220 (calc II)/Integration with Trig Identities.md @@ -4,7 +4,10 @@ The below integration makes use of the following trig identities: 3. The derivative of cosine: $\dfrac{d}{dx} \cos(x) = -\sin(x)$ 4. Half angle cosine identity: $\cos^2(x) = \frac{1}{2}(1 + \cos(2x))$ 5. Half angle sine identity: $\sin^2(x) = \frac{1}{2}(1 - \cos(2x))$ -6. $tan^2(x) + 1 = sec^2(x) \Rightarrow \int \sec^2(x)$ -7. $\dfrac{d}{dx}(\tan(x)) = \sec^2(x)$ -8. +6. $tan^2(x) + 1 = sec^2(x)$ +7. $\dfrac{d}{dx}(\tan(x)) = \sec^2(x) \Rightarrow \int \sec^2(x)dx = \tan(x) + C$ +8. $\dfrac{d}{dx}(\sec x) = \sec(x)\tan(x) \Rightarrow \int\sec(x)\tan(x) dx = \sec(x) + C$ +# Examples +> Evaluate the integral $\int\sin^5(x)dx$ +1. With trig identities, it's common to work *backwards* with u-sub, so we know that \ No newline at end of file