Mathematics

Mathematics

Problem

A sector of a circular sheet of metal has an area of 154 cm2154\,\text{cm}^2. The radius of the original circular sheet is 14 cm14\,\text{cm}. a. (i) Determine the central angle of the sector. b. (ii) Find the length of the curved edge of the sector.
Intuitive explanation

The key is recognizing that a sector is just a "slice" of the circle, and its area is proportional to the angle it subtends. Use the sector area formula A=θ360°×πr2A = \frac{\theta}{360°} \times \pi r^2 (or with radians) to find what fraction of the full circle this sector represents, then solve for the central angle θ\theta. Once you have the angle, you can find any other property of that sector, like its arc length or perimeter.

Intuitive explanation

The key is recognizing that a sector is just a "slice" of the circle, and its area is proportional to the angle it subtends. Use the sector area formula A=θ360°×πr2A = \frac{\theta}{360°} \times \pi r^2 (or with radians) to find what fraction of the full circle this sector represents, then solve for the central angle θ\theta. Once you have the angle, you can find any other property of that sector, like its arc length or perimeter.

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