Question 2:
A right triangle whose sides are 3 cm and 4 cm (other than hypotenuse) is made to revolve about its hypotenuse. Find the volume and surface area of the double cone so formed. (Choose value of π as found appropriate.)
Answer:
The double cone so formed by revolving this right-angled triangle ABC about its hypotenuse is shown in the figure.
Surface area of double cone = Surface area of cone 1 + Surface area of cone 2
= πrl1 + πrl2
= πr [4 + 3] = 3.14 × 2.4 × 7 = 52.75 cm2
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