Question

Total surface area of a sphere is 40 square centimetres. The sphere is divided into two hemispheres.

c) What is the ratio between the surface areas of a hemisphere and a sphere having the same radius?

a) What is the area of the plane surface of a hemisphere?

b) What is the total surface area of a hemisphere


Plz answer the question with steps​

Answer 1

Answer:

a. 1:2

b. 10cm²

c. 20cm²

Step-by-step explanation:

surface area of sphere =40 cm²

4Πr² = 40

Πr²=40/4

3.14×r²=10

r² =10/3.14

r²=3.185 cm

b) total surface area of hemisphere =2Πr²

= 2×3.14×3.185

= 20 cm²

a. surface area of hemisphere /surface area of sphere =20/40

=1/2

ans. 1:2

area of plane surface of hemisphere =Πr²

=3.14×3.185

=10 cm²

Answer 2

Answer:

$4\pi \times r {}^{2} = 40$

$\pi \times r {}^{2} = 40 \div 4 = 10$