Part 1/5:

Understanding Trigonometric Identities

In the realm of mathematics, particularly in trigonometry, understanding various identities is crucial for simplifying expressions and solving equations. This article explores fundamental trigonometric identities focusing on the behavior of sine and cosine with respect to negative angles.

Sine and Cosine of Negative Angles

One of the most important identities in trigonometry is how sine and cosine function when angles are negative. Specifically, the sine of a negative angle can be expressed as:

sin(-θ) = -sin(θ)

Similarly, the cosine of a negative angle is represented as:

cos(-θ) = cos(θ)