GCSE Maths Practice: perimeter-and-area

Question 7 of 10

This question calculates the radius of a circle given its area in terms of π.

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\( \begin{array}{l}\text{If the area of a circle is } 49\pi\,\text{cm}^2, \text{ what is the radius?}\end{array} \)

Choose one option:

\( 7\,\text{cm} \) \( 14\,\text{cm} \) \( 3.5\,\text{cm} \) \( 9\,\text{cm} \)

Remove π first, then take square root. Always check units.

When given the area of a circle in terms of π, use the formula A = πr² to solve for r. For example, A = 49π cm² → r² = 49 → r = 7 cm. Understanding how to manipulate formulas and solve for unknown variables is crucial in circle geometry. Practice with different area values helps develop confidence in isolating the radius and checking units. This method applies to real-life situations like finding the radius of circular objects, pipes, and wheels when the area is known.