Q3 of 52 Page 148

The circumferences of circular faces of a frustum are 132 cm and 88 cm and its height is 24 cm. To find the curved surface area of the frustum complete the following activity.


Circumference1 = 2πr1 = 132



Circumference2 = 2πr2 = 88



Slant height of frustum,



Curved Surface area of frustum = π(r1 + r2)l


Circumference1 = 2πr1 = 132



Circumference2 = 2πr2 = 88



Slant height of frustum,






Curved Surface area of frustum = π(r1 + r2)l


⇒ Curved Surface Area of frustum = π× (21 + 14) × 25


⇒ Curved surface area = π × 35 × 25 = 2750 sq. cm


More from this chapter

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1

The radii of two circular ends of frustum shape bucket are 14 cm and 7 cm. Height of the bucket is 30 cm. How many liters of water it can hold? (1 litre = 1000cm3)

 2

The radii of ends of a frustum are 14 cm and 6 cm respectively and its height is 6 cm. Find its

i) Curved surface area


ii) Total surface area


iii) Volume

 1

Radius of a circle is 10 cm. Measure of an arc of the circle is 54°. Find the area of the sector associated with the arc. (π = 3.14)

 2

Measure of an arc of a circle is 80 cm and its radius is 18 cm. Find the length of the arc. (π = 3.14)