Question

how many metres of cloth 2.5 m widewill be required to make a conical tent whose base radius is 7m and height 24m

Answer 1

mayb it's like this,,

l^2 = h^2 + r^2 = 576 + 49 = 625
l = 25
now,
ar. of cloth = l.s.a of tent
2.5 * length = 22/7 * 7 * 25 
hence length = 220 m 

Answer 2

use pythagarous theorm

l^2 = h^2 + r^2
so you get l=25
that is required height
by this problem
you form eqn
 cloth area= l.s.a of tent
2.5 * length = 22/7 * 7 * 25 
solving the equation
you get length is 220 m