Question

Find the diameter of a circle whose area is 628 square cm (use π = 3.14).

Answer 1

Area = πr² = 628

Therefore

3.14 × r² = 628

314/100 × r² = 628

r² = 628 × 100/314

r² = 2 × 100

r² = 200

r = √200

r = 10√2

Diameter = 2r = 2 × 10√2 = 20√2 cm

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Answer 2

Given,
Area of circle = pir²

$= > \pi {r}^{2} = 628 {cm}^{2} \\ = > {r}^{2} = \frac{628}{3.14} \\ = > r = \sqrt{200} \\ = > r = 10 \sqrt{2}cm \\ = > 2r = 20 \sqrt{2}cm \\ = > d = 20 \sqrt{2}cm.$



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