Mathematics for IGCSE & O level - Mensuration (Section 5 - No. 6)
Which of the following must be known to calculate the area of a circle?
The radius of the circle
The diameter of the circle
The circumference of the circle
The length of a side
คำอธิบาย
Area can be calculated using radius or diameter, because the diameter is twice the radius. The circumference and the length of a side don't help determine the area of the circle.