The slant height of the frustrum of a cone is 4 cm. If the perimeters of its circular bases be 18 cm and 6 cm, find the curved surface area of the frustum and also find the cost of painting its total surface at the rate of rs. 12.50 per 100cm2.
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Answer:
Step-by-step explanation:
Slant height = l=4cm
R=?
r=?
2πR=18cm
22/7 *2 R=18cm
2R=18*7/22
2R=5.727
R=2.86
2πr=6cm
2*22/7*r=6
2r=6*7/22
2r=1.90
r=0.95
CSA of frustum=π(r+R)l
=22/7(0.95+2.86)*4
=22/7*3.81*4
=47.89cm^2
TSA of frustum=π(r+R)l+πr^2+πR^2
=47.88cm^2+22/7(0.95)^2+22/7(2.86)^2
=47.88+22/7*0.9025+22/7*8.1796
=47.88+2.83+25.7
=76.41cm^2
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