Question

Mark (✓) against the correct answer
The area of a circle is 154 cm². Its diameter is

(a) 14 cm
(b) 11 cm
(c) 7 cm
(d) 22 cm

Answer 1

(a) 14 cm

Let the radius of the circle be r cm.
Then, its area will be $\left({\mathrm{\pi r}}^2\right)$ cm².
∴ ${\mathrm{\pi r}}^2$ = 154
⇒ $\left(\frac{22}{7}\times r\times r\right)$ = 154
⇒ r² = $\left(\frac{154\times 7}{22}\right)$ = 49
⇒ r = $\sqrt{49}$ = 7 cm
∴ Diameter of the circle = 2r = (2 × 7) cm = 14 cm