Question

C The height of a cone is 16cm and its slant height is 20cm Find the
D
radius of its base
total surface area​

Answer 1

Answer:

Radius = 12 cm

Total surface area= 1205.76 cm²

Step-by-step explanation:

We know that,

l²= h²+r²

r²=l²-h²

r=√[(l-h)(l+h)]

r= √(20-16)(20+16)

r= √(4×36)

r= 2× 6

r = 12 cm

Total surface area of cone = πr(r+ l)

= 3.14×12(12+20)

= 37.68× 32

= 1205.76 cm²

Answer 2

Given :-

• Height of the cone is 16 cm

• Slant height is 20 cm

To Find :-

• Radius of its base

• Total surface area

Solution :-

~Here, we're given the height and slant height of a cone and we need to find the radius of it's base and total surface area. Firstly we will find radius of the base by putting the values in the formula of slant height and then total surface area by putting values in it's formula.

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As we know that ,

★ Slant height = √ h² + r²

★ Total surface area = πr( r + l )

Where,

• h is height

• r is base radius

• l is slant height

• π is 3.14

Finding the base radius :-

⟶  20 = √ 16² + r²

⟶  20² = 16² + r²

⟶  400 = 256 + r²

⟶  r²  = 400 - 256

⟶  r² = 144

⟶  r = √144

⟶  r = 12 cm

Finding the total surface area :-

⟶  3.14 × 12 × ( 12 + 20 )

⟶  3.14 × 12 × 32

⟶  1025.76 cm²

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Hence,

• Radius of its base is 12 cm and total surface area is 1025.76 cm²

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