Surface area of a cone is 188.4 sq.cm and its slant height is 10cm. Find its perpendicular height ( = 3.14)
Answers
Solution :
Dimensions of the cone :
i ) Slant height ( l ) = 10 cm
Let the height = h cm
Radius = r cm
Surface area of the cone = 188.4 sqcm
=> πrl = 188.4
=> r = 188.4 /( πl )
=> r = 188.4/( 3.14 × 10 )
r = 6 cm
ii ) r = 6 cm , l = 10 cm , h = ?
h² = l² - r²
=> h² = 10² - 6²
=> h² = 100 - 36
=> h² = 64
h = √64
h = 8 cm
Therefore ,
Perpendicular height of the
cone = h = 8 cm
••••
≡QUESTION≡
The curved surface area of a cone is 188.4 cm² and its slant height is 10 cm. Find its perpendicular .
║⊕ANSWER⊕║
GIVEN
Slant height ( l ) = 10 cm
Surface area of the cone = 188.4 cm²
Let the height be h cm
Radius = r cm
πrl = 188.4
r = 188.4 /( 3.14 * 10)
r = 188.4/( 3.14 * 10 )
r = 6 cm
Height is given by the formula:
h² = l² - r²
= 10² - 6²
= 100 - 36
= 64
h = √64
= 8 cm
∴ The perpendicular height of the cone = 8 cm