Junior Class 1 Answered

the ration of curved surface area to the total surface area is to the ratio of 1:3 find the radius and hieght of the cylinder if its total surface area is 1848 cm sq? (pie = 22/7) ! whts the answer ?

Asked by juweriya ahmed | 09 Feb, 2016, 06:19: PM

Expert Answer

$Let space straight r space be space the space radius space and space straight h space be space the space height space of space the space cylinder. Curved space surface space area space of space cylinder space equals 2 space πrh Total space surface space area space of space cylinder space equals space 2 space πrh plus 2 πr squared the space ratio space of space curved space surface space area space to space the space total space surface space area space is space to space the space ratio space of space 1 colon 3 space fraction numerator 2 space πrh over denominator space 2 space πrh plus 2 πr squared end fraction equals 1 third straight h equals 1 third open parentheses straight h plus straight r close parentheses 2 straight h space equals space straight r Total space surface space area space is space 1848 space cm squared space 2 space πrh plus 2 πr squared space equals 1848 2 cross times 22 over 7 cross times straight r cross times straight r over 2 plus 2 cross times 22 over 7 cross times straight r squared equals 1848 3 over 2 straight r squared equals 294 straight r squared equals 196 straight r equals 14 space cm space 2 straight h space equals straight r straight h equals straight r over 2 equals 7 space cm height space is space 7 space cm space and space radius space is space 14 space cm.$