Question

find the circumference and area of a semi circle of radius 5 cm.​

Answer 1

Answer:

• Circumference of the semi-circle is 25.71 cm.
• Area of the semi-circle is 39.28 cm².

Step-by-step explanation:

Given that:

• Radius of a semicircle is 5 cm.

To Find:

• Circumference and area of the circle.

Formulas Used:

• Circumference of a semi-circle = (1/2 × 2πr) + d
• Area of a circle = 1/2 × πr²

Where,

• r = Radius
• d = Diameter

Solution:

Diameter of the semi-circle = 2r = 2 × 5 = 10 cm

Circumference of the semi-circle = 1/2 × 2πr + d

Substituting the values,

$\sf{= \bigg(\dfrac{1}{2}\times2\times\dfrac{22}{7}\times 5\bigg)+10}$

Reducing the numbers,

$\sf{= \bigg(\dfrac{22}{7}\times 5\bigg)+10}$

Multiplying the numbers,

$\sf{= \dfrac{110}{7}+10}$

Adding the numbers,

$\sf{=\dfrac{110+70}{7}}$

$\sf{= \dfrac{180}{7}}$

Dividing 180 by 7,

$\sf{= \boxed{25.71}}$

Hence, circumference of the semi-circle is 25.71 cm.

Now,

Area of the semi-circle = 1/2 × πr²

Substituting the values,

$\sf{= \dfrac{1}{2}\times\dfrac{22}{7}\times5^2}$

$\sf{= \dfrac{1}{2}\times\dfrac{22}{7}\times5\times5}$

Multiplying the numbers,

$\sf{=\dfrac{550}{14}}$

Dividing 550 by 14,

$\sf{= \boxed{39.28}}$

Hence, area of the semi-circle is 39.28 cm².

Answer 2

Answer:

Solution :-

Area = πr²

22\7 x 5 x 5

=78.57143cm²

Semi - circle means circle divided into two

So, 78.57143 ÷ 2

= 39.285715cm² or 39.29cm² ( Ans )

circumference :-

Circumference - 2πr

2 x 22\7 x 5

= 31.42857cm

Diameter - 5 x 2 = 1Ocm

Think figure in mind & diagonal the diameter .

Then , 1\2 x 31.42857cm

= 15.714285 + 1O cm

= 25.714285cm or 25.71cm ( Ans )

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