Question

the slant height of the frustum of a cone is 5 cm . if the difference between the radii of its two circular ends is 4 cm find the height of the frustum

Answer 1

slant height = 5 cm
R1-R2 =4cm
h=x

l =root of R1-R2(sq) + h(sq)

sq on both side

${5}^{2} = {4}^{2} + {x}^{2}$

x(sq)=25-16
x(sq)=9
x=3cm

Answer 2

Let r and R be the radii of the circular ends of the frustum of the cone and h be the height of the frustum.

R-r = 4 and l = 5 cm 

l² = (R-h)² + h²

5² = 4² + h²

h² = 25 - 16 

h² = 9 

h= 3 

Hence , height of the frustum is 3 cm