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The area of a sector of a circle of radius 36 cm is 72π72\pi cm². Find the length of the corresponding arc of the sector.

Solution

✅ Correct Option: 1

The radius of the circle is 36 cm and the area of the sector is 72π72\pi cm².

The area of a sector is given by:

Area of sector=θ360°×πr2\text{Area of sector} = \frac{\theta}{360°} \times \pi r^2

where θ\theta is the angle of the sector in degrees.

72π=θ360°×π×(36)272\pi = \frac{\theta}{360°} \times \pi \times (36)^2

72π=θ360°×π×129672\pi = \frac{\theta}{360°} \times \pi \times 1296

72=θ360°×129672 = \frac{\theta}{360°} \times 1296

θ360°=721296\frac{\theta}{360°} = \frac{72}{1296}

θ360°=118\frac{\theta}{360°} = \frac{1}{18}


The arc length is given by:

Arc length=θ360°×2πr\text{Arc length} = \frac{\theta}{360°} \times 2\pi r

Arc length=118×2π×36\text{Arc length} = \frac{1}{18} \times 2\pi \times 36

Arc length=118×72π\text{Arc length} = \frac{1}{18} \times 72\pi

Arc length=4π\text{Arc length} = 4\pi cm


Therefore, the answer is Option 1: 4π4\pi cm.

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