Question

If the circumference of a circle exceeds its diameter by 180 cm, then find its radius in cm. (Take $\pi =\frac{22}{7}$)

• A. 32
• B. 36
• C. 40
• D. 42

Answer 1

The correct option is D

42

Let the radius of the circle be r cm.

The circumference of the circle with radius r is given by
$2\pi r.$

So,
$2\pi r=d+180$

$2\pi r=2r+180$

$r=\frac{180}{2(\pi -1)}$

$r=\frac{180}{2(\frac{22}{7}-1)}$

$r=\frac{90}{2\times \frac{15}{7}}=42cm$