Question

The height of a right circular cylinder is 12.6cm. Three times the sum of these areas of its two circular faces is twice the area of the curved surface. Find the volume of cylinder.



I need full answer please​

Answer 1

h=12.6cm

3(2πrr)=2(2πrh)

6r=4h

6r=4*12.6

r=4×12.6/6

r=4×2.1

r=8.4cm

volume=πr∆2h

=279.4176cm∆3.

Answer 2

${\huge {\mathfrak {Answer :-}}}$

➡️ Let the radius be 'r' and height 'h'.

So, Sun of surface area of two circular faces is

= 2* $\pi$ * r^2

And the surface area of curved surface is

= 2 * $\pi$ * r * h

Given that,

3 (2 * $\pi$ * r^2) = 2 (2 * $\pi$ * r * h)

Or, 3 * 2 * 22/7 * r^2 = 2 * 2 * 22/7 * r * 12.6

Or, 3 * r = 2 * 12.6

Or, r = 2 * 4.2 = 8.4

So, the radius is 8.4 cm.

➡️ Now, Volume is

= $\pi$ * r^2 * h

= 22/7 * 8.4 * 8.4 * 12.6 Cu.cm

= 2794 Cu.cm.

That's it..