Step 1: Understand that cosine is a function used in trigonometry to find the ratio of the adjacent side to the hypotenuse in a right triangle.
Step 2: Recall that a 60-degree angle is a common angle in trigonometry.
Step 3: Remember the special triangle: in a 30-60-90 triangle, the sides are in the ratio 1 (opposite 30 degrees) : √3 (opposite 60 degrees) : 2 (hypotenuse).
Step 4: For a 60-degree angle, the adjacent side is 1 (the side opposite the 30-degree angle) and the hypotenuse is 2.
Step 5: Use the cosine formula: cosine of 60 degrees = adjacent side / hypotenuse = 1 / 2.
Step 6: Simplify the fraction: 1 / 2 = 0.5.
Step 7: Conclude that the cosine of a 60-degree angle is 0.5.
