Question

the base radius of cylider is 21 cm if its height is 20 cm find the curved surface area solve i

Answer 1

$\bigstar$ Given:-    

• The base radius of the cylinder is 21 cm
• The height of the cylinder is 20 cm

$\bigstar$ To find:-    

• The curved surface area

$\bigstar$ Formula Used:-      

• $\Large\boxed{\underline{\tt{Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:2\:\pi\:r\:h}}}$

where,

• r = radius
• h = height
• π = pi

$\bigstar$ Solution:-      

Here we have the base radius of the cylinder is 21 cm and its height is 20 cm to find out the curved surface area we will use the formula and substitute the values. ( curved surface area = 2πrh )

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:2\:\pi\:r\:h}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:2\:\times\:\pi\:\times\:20\:\times\:21}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:2\:\times\:\pi\:\times\:420}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:\pi\:\times\:840}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:\dfrac{22}{7}\:\times\:840}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:22\:\times120\:}$

$\qquad\tt{:\implies\:Curved\:surface\:area\:_{(\:\:CYLINDER\:\:)}\:=\:2,640\:cm^{2}\:}$

. ° . Thus the curved surface area is 2640 cm².

Answer 2

Step-by-step explanation:

A≈ 5409.82cm²

r=Radius

cm=h

h=Heightcm

Solution

A=2πrh + 2 r 2 =2··π21·20+2·π·212

≈

5409.82255cm²

$\:$

Hope it helps you mate