Answer:
The radius of cylinder is 1.05 cm and
The height of cylinder is 2.11 cm
Explanation:
Given as :
The total surface area of cylinder = 21 cm
The curved surface area of cylinder =
of the total surface area
I.e The curved surface area of cylinder =
× 21 = 14 cm
∵ The total surface area of cylinder = 2
r h + 2
r²
Where r is the radius and h is the height of cylinder
Or, 2
r h + 2
r² = 21 cm
Or,
= 21 cm ....a
Again ∵ The curved surface area of cylinder = 2
r h
Where r is the radius and h is the height of cylinder
Or, 2
r h = 14 cm . ...b
so . put the value of a into b
I.e 14 cm +
= 21 cm
Or,
= 21 cm - 14 cm
Or,
= 7
so , r² =

∴ r² =

I.e r =

So, radius =
cm
or, r = 1.05 cm
Put the value of r in eq b
2
r h = 14 cm
Or, 2
×
× h = 14 cm
So, h =

Or, h = 2.11 cm
Hence The radius of cylinder is 1.05 cm and The height of cylinder is 2.11 cm Answer