✔ 最佳答案
Question 1:
Consider small cone VAB and big cone VAB
Frustum Y = Volume of big cone – Volume of small cone
Volume of big cone = 1/3 x pi x r2^2 x h2
(where r2 is radius of the big cone and h2 is its height)
Volume of small cone = 1/3 x pi x r2^2 x h1 = 40 cm^3
(where r1 is radius of the big cone and h1 is its height)
Consider triangle VAE and triangle VCF where E is the centre of the circular base of the small cone and F is the centre of the circular base of the big cone
Triangle VAE and triangle VCF are similar triangles; Using ratio,
Since VA:AC=2:1, so VA:VC = 2:3
AE : AF = r1: r2 = 2:3, so r2 = 3/2 r1
VE : VF = h1: h2 = 2:3, so h2 = 3/2 h1
Volume of Frustum Y = Volume of big cone – Volume of small cone
Vol. of Frustum Y = 1/3 x pi x r2^2 x h2 – 40 cm^3
Substitute r2=3/2 r1 and h2 = 3/2 h1 into above equation
Vol. of Frustum Y = 1/3 x pi x (3/2r1)^2 x 3/2 h1 – 40 cm^3
Vol. of Frustum Y = 1/3 x pi x 9/4 x r1^2 x 3/2 h1 – 40 cm^3
Vol. of Frustum Y = 27/ 8 x (1/3 x pi x r1^2 x h1) – 40 cm^3
(Note: volume of small cone = 1/3 x pi x r1^2 x h1 = 40 cm^3)
Vol. of Frustum Y = 27/8 x 40 cm^3 – 40 cm^3
Vol. of Frustum Y = 135 cm^3 – 40 cm^3
Vol. of Frustum Y = 95 cm^3
Note: pi = 3.14159; x is multiplication sign; ^ is “raised to”
Question 2: What is EGG?
