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Q1:
Find the area of a sector of a circle with radius 6 cm if angle of the sector is 60°. (Unless stated otherwise, use $\pi = \frac{22}{7}$)

Solution :

Given:

Radius of the circle ($r$) = $6\text{ cm}$

Angle of the sector ($\theta$) = $60^\circ$

Value of $\pi = \frac{22}{7}$

To find:

The area of the sector of the circle.

6 cm 60° O

Step 1: State the formula for the area of a sector.

The area of a sector of a circle with radius $r$ and central angle $\theta$ (in degrees) is given by the formula:

$\text{Area of sector} = \frac{\theta}{360^\circ} \times \pi r^2$

[Justification: The area of a sector is a fraction of the total area of the circle ($\pi r^2$), where the fraction is determined by the ratio of the sector's angle to the total angle of a circle ($360^\circ$)]

Step 2: Substitute the given values into the formula.

Substituting $r = 6$, $\theta = 60^\circ$, and $\pi = \frac{22}{7}$:

$\text{Area} = \frac{60}{360} \times \frac{22}{7} \times (6)^2$

Step 3: Perform the arithmetic calculations.

First, simplify the fraction $\frac{60}{360}$:

$\frac{60}{360} = \frac{1}{6}$

[Since $60 \times 6 = 360$]

Next, calculate the square of the radius:

$6^2 = 36$

Now, substitute these back into the expression:

$\text{Area} = \frac{1}{6} \times \frac{22}{7} \times 36$

Step 4: Simplify the final expression.

$\text{Area} = \frac{1 \times 22 \times 36}{6 \times 7}$

Divide $36$ by $6$:

$\text{Area} = \frac{22 \times 6}{7}$

[Since $36 \div 6 = 6$]

$\text{Area} = \frac{132}{7}$

[Since $22 \times 6 = 132$]

Converting to decimal form (optional, but standard for verification):

$\text{Area} \approx 18.857\text{ cm}^2$

Final Answer: The area of the sector is $\frac{132}{7}\text{ cm}^2$ (or approximately $18.86\text{ cm}^2$).


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