Question

if the total surface area of cylinder is 528cm sq. and height is 8cm. Find the radius of its base and its curved surface area.

Answer 1

Answer:

r = 6 cm    ,   curved surface area  = 2112/7 sq.cm

Step-by-step explanation:

height is 8cm.

Total surface area of cylinder = 528 sq.cm

2πr (r+h) = 528

2*22/7 * r (r+8) = 528

44/7 * $r^{2}$ + 8r  =528

$r^{2}$ + 8r = 528 *7 /44

$r^{2}$ + 8r = 84

$r^{2}$ + 8r - 84 =0

$r^{2}$ - 6r + 14r - 84 = 0

r ( r - 6 ) +14 ( r - 6 )

( r - 6 ) ( r + 14 )

so , r = 6 , -14

the radius never in negative

r = 6 cm

curved surface area = 2$\pi$rh

                                 =   2*22/7*6*8

                                 =   2112/7 sq.cm