A top is of the shape of a cone over a hemisphere. The radius of the hemisphere is 3.5 cm. The total height of the top is 15.5 cm. Find the total area of the top.
Answer & explanation
Correct answer: option 1
Height of cone = 15.5 – 3.5 = 12 cm
$l=\sqrt{h^2+r^2}$
$=\sqrt{(3.5)^2+(12)^2}=12.5cm$
C.S.A. = $πrl$ = 137.5 sq cm C.S.A. of hemisphere = $2πr^2=77cm^2$
∴ Total area of the top = 214.5 sq. cm.