A toy is in the form of a cone mounted on a hemisphere. The radius of the hemisphere and that of the cone is 7 cm and height of the cone is 5 cm. The total surface area of the toy (take 7 = =) is (rounded off to two places of decimal):
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 497.25 cm2
Given that
The radius of the hemisphere = 7 cm
The height of the cone = 5 cm
The total surface area of the toy = the surface area of the cone + the surface area of the hemisphere
Formula used
The curved Surface Area, CSA of cone = πrl
The curved surface area of the hemisphere = 2πr2 square units.
Now, The total surface area of the toy = πrl + 2πr2
= 2 × (22/7) × 72 + (22/7) × 7 × √(72 + 52)
= 389 + 189.25 = 497.25 cm2