Question

3. Find the base radius of a right circular cylinder whose whole surface is 231 cm and the curved surface is
of the whole surface.
3/2 of the whole surface

Answer 1

Answer:

PLZ MARK AS BRAINLIEST !

Step-by-step explanation:

The Total Surface Area of the right circular cylinder is  

231 cm2 = 2πrh + 2πr² ………….(1)  

The curved surface area of the cylinder is 2πrh

Given:  

The curved surface area is 2/3 of TSA

Thus;  

2/3 × (2πrh + 2πr²) = 2πrh  

2/3 × 2πr (h + r ) = h × 2πr  

Diving both sides by 2πr  

2/3 (h + r) = h  

2h + 2r = 3h    

h = 2r …………………………(2)

Eq 1 states:  

2πrh + 2πr² = 231    

2πr × (h + r) = 231  

But h = 2r

Substituting the value of Eq. 2 in Eq. 1  

2πr × (2 r + r) = 231  

2πr × 3r = 231  

6 × 22/7 × r^2 = 231  

r^2 = 12.25  

r = 3.5 cm

∴ Thus, the base radius of the cylinder is 3.5 cm