What is the sine of 90 degrees?

The sine of 90 degrees is equal to 1. This is derived from the unit circle in trigonometry. In the unit circle, the angle of 90 degrees (or π/2 radians) corresponds to the point (0, 1). The sine function represents the y-coordinate of a point on the unit circle. Therefore, at 90 degrees, the y-coordinate is 1, which means that the sine of 90 degrees is indeed 1.

Understanding this concept is important in trigonometry as it illustrates the relationship between angles and their corresponding values on the unit circle, which is foundational for further studies in mathematics and science.