Trigonometric Identities Review

$$\text{sin}^2\theta + \text{cos}^2\theta = 1$$

$$\text{sec}\theta = \frac{1}{\text{cos}\theta}$$

$$\text{csc}\theta = \frac{1}{\text{sin}\theta}$$

$$\text{tan}\theta = \frac{\text{sin}\theta}{\text{cos}\theta}$$

$$\text{sin}(2\theta) = 2\text{sin}\theta \text{cos}\theta$$

$$\text{cos}(2\theta) = \text{cos}^2\theta - \text{sin}^2\theta$$ or $$\text{cos}(2\theta) = 2\text{cos}^2\theta - 1$$ or $$\text{cos}(2\theta) = 1 - 2\text{sin}^2\theta$$

$$\text{cot}\theta = \frac{\text{cos}\theta}{\text{sin}\theta}$$

$$\text{csc}\theta = \frac{1}{\text{sin}\theta}$$

$$\text{sec}\theta = \frac{1}{\text{cos}\theta}$$

$$\text{sin}^2\theta + \text{cos}^2\theta = 1$$