Mathematics for IGCSE & O level - Similarity (Section 1 - No. 4)
The area of a circle is 100π cm². If we scale the radius by a factor of 2, what is the new area?
200π cm²
300π cm²
400π cm²
800π cm²
Giải thích
If the radius is doubled, the area is quadrupled, thus 100π * 4 = 400π cm²