The total perimeter of a semicircle Is 20.6 cm. What is the approximate radius of the semi-circle ?
- 4 cm
- 5cm
- 6.6 cm
- None of these
Explanation
Perimeter = πr + 2r
where:
π is a mathematical constant approximately equal to 3.14159
r is the radius of the semicircle
In this problem, we know the total perimeter is 20.6 cm. So we can set up the equation:
20.6 = πr + 2r
To solve for r, we can factor out r on the right side:
20.6 = r(π + 2)
Then, we can divide both sides by π + 2 to isolate r:
r = 20.6 / (π + 2)
Using a calculator to evaluate this expression, we get:
r ≈ 4.0 cm
Therefore, the approximate radius of the semicircle is 4 cm.
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