Question

A child looking into a small, polished, hemispherical metal bowl sees an
erect image of himself 21 cm from the bowl. He turns the bowl over and
sees a further erect image of himself 7cm from the bowl. What is the
radius of the curvature of the bowl?​

Answer 1

Answer:

Thickness =0.25cm

Inner radius =5cm

∴ Outer radius =5+0.25=5.25cm

⇒Outer Curved Surface Area =2πr

2

=2×

7

22

×5.25×5.25

=173.25