Question

Find the central angle of a sector of a circle of the area of the sector and the area of the circle are in the proportion of 3:5

Answer 1

Answer:

$\theta = 216$

Step-by-step explanation:

Given

Area of Sector : Area of Circle = 3 : 5

Required

Determine the central angle

The question implies that

$\frac{Area_{sector}}{Area_{circle}} = \frac{3}{5}$

Multiply both sides by 5

$5 * \frac{Area_{sector}}{Area_{circle}} = \frac{3}{5} * 5$

$5 * \frac{Area_{sector}}{Area_{circle}} = 3$

Multiply both sides by Area{circle}

$5 * \frac{Area_{sector}}{Area_{circle}} * Area_{circle} = 3 * Area_{circle}$

$5 * {Area_{sector} = 3 * Area_{circle}$

Substitute the areas of sector and circle with their respective formulas;

$Area_{sector} =\frac{\theta}{360} * \pi r^2$

$Area_{circle} = \pi r^2$

So, we have

$5 * \frac{\theta}{360} * \pi r^2 = 3 * \pi r^2$

Divide both sides by $\pi r^2$

$5 * \frac{\theta}{360} * \frac{ \pi r^2}{\pi r^2} = 3 * \frac{\pi r^2}{\pi r^2}$

$5 * \frac{\theta}{360} = 3$

Multiply both sides by 360

$360 * 5 * \frac{\theta}{360} = 3 * 360$

$5 * \theta = 3 * 360$

Divide both sides by 5

$\frac{5 * \theta}{5} = \frac{3 * 360}{5}$

$\theta = \frac{3 * 360}{5}$

$\theta = \frac{1080}{5}$

$\theta = 216$

Hence, the central angle is 216 degrees