Question: (a) Given a circular sector with radius L and central angle (see figure), show that the area of the sector is given by S
(a) Given a circular sector with radius L and central angle θ (see figure), show that the area of the sector is given by S = 1/2 L2θ.
(b) By joining the straight-line edges of the sector in part (a), a right circular cone is formed (see figure) and the lateral surface area of the cone is the same as the area of the sector. Show that the area is S = πrL, where r is the radius of the base of the cone.

(c) Use the result of part (b) to verify that the formula for the lateral surface area of the frustum of a cone with slant height L and radii r1 and r2 (see figure) is S = π(r1 + r2)L.

Figure for 56(a) Figure for 56(b)
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ANSWER a The area of a sector is given by A 12 r2 where r is the radius and is the central angle in ... View full answer
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