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Step-5

Title: Semi-circles

Grade: 8-a Lesson: S4-L5

Explanation: Let us verify the answer here with the steps.

Description:

Step	Type	Explanation	Answer
1	Problem	Find the radius of a semi-circle with an area of 25 sq cm.(Use π = 3.14)
2	Hint	Formula used	\$"Area" = 1/2 (\pi \times r^2)\$
3	Step	The area of a semi-circle is	25 cm
4	Hint	We know that, the area of a semi-circle	\$"Area" = 1/2 (\pi \times r^2)\$
5	Step	The area of a semi-circle (A) =	\$25 = 1/2 (\pi \times r^2)\$ ⇒ \$25 \times 2 = π \times r^2\$ ⇒ \$(50)/π = r^2\$ ⇒ \$(50)/(3.14) = r^2\$ ⇒ \$(50)/(3.14) = r^2\$ ⇒ \$15.923 = r^2\$ ⇒ \$\sqrt(15.923) = r\$ ⇒ \$3.99 = r\$
6	Step	Hence, the radius of a semi-circle is	3.99 cm

Step

Type

Explanation

Answer

Problem

Find the radius of a semi-circle with an area of 25 sq cm.(Use π = 3.14)

Hint

Formula used

\$"Area" = 1/2 (\pi \times r^2)\$

Step

The area of a semi-circle is

25 cm

Hint

We know that,

the area of a semi-circle

\$"Area" = 1/2 (\pi \times r^2)\$

Step

The area of a semi-circle (A) =

\$25 = 1/2 (\pi \times r^2)\$

⇒ \$25 \times 2 = π \times r^2\$

⇒ \$(50)/π = r^2\$

⇒ \$(50)/(3.14) = r^2\$

⇒ \$15.923 = r^2\$

⇒ \$\sqrt(15.923) = r\$

⇒ \$3.99 = r\$

Step

Hence, the radius of a semi-circle is

3.99 cm