Question

find the volumw of a cone having height21cm and slant height28cm
who ans this i will mark as ​

Answer 1

By Pythagoras theorem,

(slant height)² = (radius )² + ( height)²

⇒radius² = (28)² - (21)²

               = (28 +21) (28- 21)

               = 49 × 7

radius = 7√7 cm

now, volume = ( π r² h)/3

                     =((22/7)× 343× 21)/3

                     = 7546 cm³

∴ volume = 7546 cm3