Answer: (1/2)r² theta.
- A r × theta
- B (1/2)r² theta
- C 2r theta
- D r² theta
Correct answer: B. (1/2)r² theta
Explanation: Area of sector = (1/2)r²θ where θ is in radians.
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