SaiBook.us Geometry

Home Course Section

Register Enroll Refer

Step-4

Title: Area of semicircle

Grade: 7-a Lesson: S1-L4

Explanation:

Step	Type	Explanation	Answer
1	Problem	The area of semi circle is \$693cm^2\$, Find the radius.?
2	Formula:	Area of a semicircle.	A = \$\frac{\pi r^2}{2}\$
3	Step	Substitute \$22/7\$ for \$pi\$ and 693 for A.	693 = \$\frac{\frac{22}{7} \times r^2}{2}\$
4	Step	Multiply.	\$693 \times \frac{7}{22} \times 2 = r^2\$
5	Step	Divide.	\$\frac{9702}{22} = r^2\$ \$\frac{\cancel9702^441}{\cancel22^1} = r^2\$
6	Step	Solve for r.	441 = \$r^2\$ \$\sqrt{441}\$ = r \$\sqrt{21^2}\$ = r
7	Step	Answer.	21 = r
8		Answer	The radius is \$21 cm\$.

Step

Type

Explanation

Answer

Problem

The area of semi circle is \$693cm^2\$, Find the radius.?

Formula:

Area of a semicircle.

A = \$\frac{\pi r^2}{2}\$

Step

Substitute \$22/7\$ for \$pi\$ and 693 for A.

693 = \$\frac{\frac{22}{7} \times r^2}{2}\$

Step

Multiply.

\$693 \times \frac{7}{22} \times 2 = r^2\$

Step

Divide.

\$\frac{9702}{22} = r^2\$
\$\frac{\cancel9702^441}{\cancel22^1} = r^2\$

Step

Solve for r.

441 = \$r^2\$
\$\sqrt{441}\$ = r
\$\sqrt{21^2}\$ = r

Step

Answer.

21 = r

Answer

The radius is \$21 cm\$.