Question

from a circle of radius 15cm,a sector with angle 216 is cut out and its bounding radii are bent so as to form a cone.find its volume

Answer 1

v = πr²h/3 .
The sectoral arc becomes the perimeter of the base circle. 
2πr = (216/360)[2πR] 
=> r/R = 216/360 
r = 15 X (216/360) 
= 216/24 = 9 cm. 
And h² = s² - r² . . . {Pythagoras theorem} 
= 15² - 9² = 3²(5² - 3²) = 3²(4²) = 12² 
h = 12 . 
Substitute the values of r, h and get V.

Answer 2

hai here is Ur perfect ans

=>given radius of sector=r=15cm

=>angle of sector=x=216°

=>length of sector=x/360×2πr

=>216/360×2×22/7×15

=>44×9/7

=>396/7cm^2

=>therefore , circumference of the circle=length of sector

=>2πr=396/7

=>2×22/7×r=396/7

=>r=396/7×7/2×1/2

=>therefore r =9 cm

=>length =15cm

=>therefore l^2=h^2+r^2

=>15^2=h^2+9^2

=>225 =h^2+81

=>h^2 =225-81

=>h^2=144

=>h=√144

=>h=12cm

=>volume =1/3πr^2h

=>1/3×22/7×9×9×12

=>66×108/7

=>7128/7

=>>1018.28cm^3


hope my ans helpfull 2 u....