Question

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pls answer if you know
volume of right circular cone is 9856 cm³ . if the diameter of the base is 28cm 1)find height of cone ,2)slant height,3) CSA of cone​

Answer 1

Ans: (i) Volume=9856 cm3

Diameter=28cm

Radius=Diameter/2

=28/2=14cm

therefore,

Volume of right circular cone=1/3πR2H

9856 =1/3 x 22/7 x 14 x 14 x H

9856 x 3 = (22 x 196)/ 7 x H

29568 = 616 x H

29568/616= H

therefore, H = 48cm _______(1)

(ii) Height = 48cm [from (1)]

Radius = 14cm

Slant height = ?

Since,

(H)2 + (R)2 = (L)2 [using pythagoras theorem for right circular cone]

(48)2 + (14)2 = (L)2

2304 + 196 = (L)2

2500 =(L)2

Therefore,

L = 50cm

(iii) Curved surface area of the cone = πRL

= 22/7 x 14 x 50

=2200cm2

Answer 2

Diameter of the base = 28cm

Radius = Diameter/2 = 28/2 = 14cm

(1). Height of cone

volume = 1/3πr²h = 9856cm3

=1/3 ×22/7 × 14 × 14 ×h = 9856cm3

=>h=48cm

(2). Slant Height

For this we can apply pythagoras theorm


r=14cm

h=48cm

r² + h² = l²

14² + 48² = l²

196 + 2304 = l²

2500 = l²

l = ✓2500

l = 50cm

(3). C.S.A.

=πrl

=22/7 × 14 × 50

=2200cm²