Lesson Example Discussion Quiz: Class Homework |
Step-4 |
Title: Arc length of sector |
Grade: 7-a Lesson: S1-L7 |
Explanation: |
Step | Type | Explanation | Answer |
---|---|---|---|
1 |
Problem |
The arc of a sector is 352m and \$\theta = 320^0\$. Find the radius? |
|
2 |
Formula: |
Arc length of a sector. |
l = \$\frac{\theta}{360^\circ} \times 2 \times \pi r\$ |
3 |
Step |
Substitute \$22/7\$ for \$pi\$, \$320^\circ\$ for \$\theta\$ and 352 for l. |
352 = \$\frac{320°}{360°} \times 2 \times \frac{22}{7} \times r\$ |
4 |
Step |
Cancel out common factor. |
\$352 = \frac{\cancel{320°} ^{8}}{\cancel{360°} ^{9}} \times 2 \times \frac{22}{7} \times r \$ |
5 |
Step |
Cancel out common factor. |
\$\cancel{352} ^{32} = \frac{8}{9} \times 2 \times \frac{\cancel {22} ^{2}}{7} \times r \$ |
6 |
Step |
Cancel out common factor. |
\$\cancel{32}^4 = \frac{\cancel{8}^1}{9} \times 2 \times \frac{2}{7} \times r \$ |
7 |
Step |
Cancel out common factor. |
\$\cancel{4}^2 = \frac{1}{9} \times \cancel{2}^1 \times \frac{2}{7} \times r \$ |
8 |
Step |
Cancel out common factor. |
\$\cancel{2}^1 = \frac{1}{9} \times 1 \times \frac{\cancel{2^1}}{7} \times r \$ |
9 |
Step |
Multiply. |
\$1 = \frac{1}{63} \times r \$ |
10 |
Step |
Solve for r. |
\$ r = 63 \$ |
11 |
Answer |
The radius is \$63 m\$. |
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