Question

the curved surface area of a cyclinder is 251.2cm square. find the radius of the its height is 8cm​

Answer 1

Question :-

$\texttt{The curved surface area of a cyclinder }$$\texttt{ is 251.2 cm². Find the radius of the}$$\texttt{ cylinder, if its height is 8 cm.}$

Answer :-

$\texttt{CSA of cylinder = 2πrh}$

$\mathtt{\implies 251.2 = 2× \Large \frac{22}{7} \normalsize × r ×8}$

$\mathtt{\implies \Large \frac{251.2×7}{2×22×8} \normalsize = r}$

$\mathtt{\implies \Large \frac{^{314} \cancel{2512}×7}{2×22×\not{8}×10} \normalsize = r}$

$\mathtt{\implies r \; = \Large \frac{^{157} \cancel{314}×7}{ \not{2} ×22×10} }$

$\mathtt{\implies r \; = \Large \frac{157×7}{22×10}}$

$\mathtt{\implies r \; = \Large \frac{1099}{220}}$

$\mathtt{\implies r \; = 4.99 cm ≈ 5 cm}$

Formulas related to Cylinder :-

$\texttt{TSA of cylinder = 2πr²+2πrh = 2πr(r+h)}$

$\texttt{CSA of cylinder = 2πrh}$

$\texttt{Vol. of cylinder = πr²h}$