Question

The area of a circle is $154$ cm². What is the circumference of the circle? 
 

• A. 22 cm
• B. 44 cm
• C. 66 cm
• D. 88 cm

Hint:

For circle problems, derive the radius from the area using $\pi r^2$, then compute the circumference using $2\pi r$.

Answer 1

The Correct Option is B

- Step 1: Area of a circle = $\pi r^2$. Given area = 154 cm², so $\pi r^2 = 154$.
- Step 2: Using $\pi \approx \dfrac{22}{7}$, we get $\dfrac{22}{7} r^2 = 154$.
- Step 3: Solve for $r^2$: $r^2 = 154 \times \dfrac{7}{22} = 49$, so $r = 7$ cm.
- Step 4: Circumference = $2\pi r = 2 \times \dfrac{22}{7} \times 7 = 44$ cm.
- Step 5: Verify: Area with $r = 7$ is $\dfrac{22}{7} \times 7^2 = 154$ cm², which matches.
- Step 6: Check options: Option (b) is 44 cm, which matches.