Question

Find the volumes of the following cylinders . ( take π = 3.14 )

Radius 3.2 cm , height 20 cm

Answer 1

Given:-

Radius of Cylinder = 3.2 cm

Height of Cylinder = 20 cm

[ Note :- π = 3.14 ]

Solution:-

Here, We know that the Volume of cylinder ⇒ πr²h

So, Volume of Cylinder ⇒ πr²h

                                       ⇒ $\dfrac{22}{7}$ × ( 3.2 cm)² × 20 cm

                                       ⇒ 3.14 × 10.24 × 20 cm²

                                       ⇒ 643.072 cm²

Hence, The Volume Of Cylinder Is 643.072 cm².

                                  $\setlength{\unitlength}{1mm}\begin{picture}(5,5)\thicklines\multiput(-0.5,-1)(26,0){2}{\line(0,1){40}}\multiput(12.5,-1)(0,3.2){13}{\line(0,1){1.6}}\multiput(12.5,-1)(0,40){2}{\multiput(0,0)(2,0){7}{\line(1,0){1}}}\multiput(0,0)(0,40){2}{\qbezier(1,0)(12,3)(24,0)\qbezier(1,0)(-2,-1)(1,-2)\qbezier(24,0)(27,-1)(24,-2)\qbezier(1,-2)(12,-5)(24,-2)}\multiput(18,2)(0,32){2}{\sf{3.2 cm}}\put(9,17.5){\sf{20 cm}}\end{picture}$

You can understand better from the above picture.

Some important terms:-

• Volume of Cylinder = πr²h

• Total Surface Area ( TSA ) of Cylinder = 2πr ( r + h )

• Curved Surface Area ( CSA ) of Cylinder = 2πrh

• The value of π is $\dfrac{22}{7}$ or 3.14 in decimal.

• You can remember these formula for your convenience :-

                          $\begin{array}{c|c|c}\cline{1-3}\bf Shape&\bf Volume\ formula&\bf Surface\ area formula\\\cline{1-3}\sf Cube&\tt l^3}&\tt 6l^2\\\cline{1-3}\sf Cuboid&\tt lbh&\tt 2(lb+bh+lh)\\\cline{1-3}\sf Cylinder&\tt {\pi}r^2h&\tt 2\pi{r}(r+h)\\\cline{1-3}\sf Hollow\ cylinder&\tt \pi{h}(R^2-r^2)&\tt 2\pi{rh}+2\pi{Rh}+2\pi(R^2-r^2)\\\cline{1-3}\sf Cone&\tt 1/3\ \pi{r^2}h&\tt \pi{r}(r+s)\\\cline{1-3}\sf Sphere&\tt 4/3\ \pi{r}^3&\tt 4\pi{r}^2\\\cline{1-3}\sf Hemisphere&\tt 2/3\ \pi{r^3}&\tt 3\pi{r}^2\\\cline{1-3}\end{array}$