Final answer:
The value of tan 60° is √3, derived from the ratio of sides in a 30°-60°-90° special right triangle.
Step-by-step explanation:
The value of tan 60° is √3. This is known from the special right triangles where the angles are 30°, 60°, and 90°. In this triangle, the side opposite the 60° angle is √3 times as long as the side opposite the 30° angle. Tangent, which is the ratio of the side opposite to the side adjacent in a right-angled triangle, therefore has a value of √3 for a 60° angle. Hence, the correct answer to the question 'What is the value of tan 60°?' is C. √3.