Answer: 90°.
- A 45°
- B 60°
- C 90°
- D 180°
Correct answer: C. 90°
Explanation: Angle in a semicircle (Thales theorem): the angle subtended at any point on the circle by the diameter is 90°.
Three standard 3D solids and their key formulas: a cylinder's volume scales with the full height, a cone's volume is exactly one-third of the cylinder with the same base and height, and a sphere's volume and surface area both follow distinct r-based formulas worth memorising separately.
Concept context
Perimeters, areas, and volumes of 2D and 3D shapes