Question

a cone of height 8 cm is to be made using a sector of circle of radius 10 cm
a) what is its central angle
b)calculate the volume and curved surface area of the cone​

Answer 1

Slant height of cone = radius of circle from which sector is cut

l=10cm

Area length of 144

0

sector = 2π×radius×

360

0

144

0

= 2π×10×

360

144

=8π

Circumference of the base of cone = arc length = 8π cm

∴ 2πr=8π⇒r=4cm

h=

l

2

−r

2

=

10

2

−4

2

=

100−16

=

84

=2

21

∴ Volume of cone =

3

1

πr

2

h=

3

1

×

7

22

×4×4×2

21

=

21

704

21