What is the cosine of \( 0^\circ \)?

The cosine of ( 0^\circ ) is defined as the x-coordinate of a point on the unit circle corresponding to an angle of ( 0^\circ ). At this angle, the point on the unit circle is at the coordinates (1, 0). Since cosine represents the x-coordinate, the value is ( 1 ). This is fundamental in trigonometry, where the cosine function measures the horizontal distance from the origin to the point on the unit circle for a given angle. Therefore, the cosine of ( 0^\circ ) is indeed ( 1 ).