What is the value of cos 0°?

The value of cos 0° is 1 because, in the context of a unit circle, the cosine of an angle corresponds to the x-coordinate of the point where the angle intersects the circle. At 0°, the point on the unit circle is at (1, 0), where the x-coordinate (cosine value) is exactly 1.

This relationship also fits within the broader context of trigonometric functions: cosine measures the ratio of the adjacent side to the hypotenuse in a right triangle, and at 0°, the adjacent side is equal to the hypotenuse, affirming that cos 0° equals 1.

This value is fundamental in trigonometry, serving as a key reference point for understanding the properties and behaviors of the cosine function across different angles.