Question

if diameter of a semi circle is 21cm2 and find its area and circumference​

Answer 1

Step-by-step explanation:

Diameter = 21

radius = 10.5

Area = πr^2

= 3.14 × 110.25

= 346.185 sq cm

Circumference = 2πr

= 2×3.14×10.5

= 3.14 × 21

= 65.94 cm

Answer 2

SOLUTION:-

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Given:

•The diameter of a semi-circle is 21cm.

To find:

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• The area of the semi-circle. &
• The area of the semi-circle. &The circumference of the semi-circle.

Explanation:

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•A semicircle is just half of a circle.

•So, the formula of the area of the semi-circle;

•Diameter of the semi-circle=21cm

•Radius of the semi-circle= 21/2

$Area = \frac{1}{2} \pi {r}^{2}$

Therefore,

$Area = \frac{1}{2} \times \frac{22}{7} \times \frac{21}{2} \times \frac{21}{2} \\ \\ Area = 11 \times 3 \times \frac{21}{4} \\ \\Area = \frac{693}{4} {cm}^{2} \\ \\ Area = 173 .25 {cm}^{2}$

&

Circumference of the semi-circle;

$= > \frac{2\pi \: r}{2}$

So,

$= > \frac{2 \times \frac{22}{7} \times \frac{21}{2} }{2} \\ \\ = > (22\times3) cm \\ \\ = > 66cm$

Thus,

• The area of the semi-circle=173.25cm²
• The circumference of the semi-circle= 66cm.

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