Geometrymedium · Past Paper
The area of a circle increases by what percent if its radius is doubled?
A100%
B200%
C300%
D400%
✓ Correct Answer: C — 300%
New Area = pi * (2r)^2 = 4 * pi * r^2. Increase = 4 - 1 = 3 times = 300%.
Share this question
More from Geometry
- If two tangents inclined at an angle of 60 degrees are drawn to a circle of radius 3 cm, then the length of each tangent is:
- The point where the three medians of a triangle intersect is called the:
- What is the supplement of an angle of 75 degrees?
- Find the area of a triangle with vertices (1, 2), (3, 4), and (10, 6).
- In a circle with center O, PT is a tangent and PAB is a secant. If PT = 6 cm and AB = 5 cm, find PA.