Question

If the height of a cylinder is equal to the radius of its base ,then the curved surface area of the cylinder is :
a)2πr b)2πr3 c)πr2 d)2πr2​

Answer 1

Answer:

d) 2πr²

Step-by-step explanation:

Curved surface area of a cylinder = 2πrh

if the height (h) is equal to radius (r) ;

then curved surface area  = 2πr×r

                                            = 2πr²

Answer 2

Answer:

• Height of cylinder = Radius of base
• Curved Surface Area = ?

Let's take the radius of base as r and height be r only as it's equal to radius of base.

$\setlength{\unitlength}{1mm}\begin{picture}(5,5)\thicklines\multiput(-0.5,-1)(26,0){2}{\line(0,1){30}}\multiput(12.5,-1)(0,3.2){10}{\line(0,1){1}}\multiput(12.5,-1)(0,30){2}{\multiput(0,0)(2,0){7}{\line(1,0){1}}}\multiput(0,0)(0,30){2}{\qbezier(1,0)(12,3)(24,0)\qbezier(1,0)(-2,-1)(1,-2)\qbezier(24,0)(27,-1)(24,-2)\qbezier(1,-2)(12,-5)(24,-2)}\multiput(18,2)(0,22){2}{\sf{r}}\put(9,11){\sf{r}}\end{picture}$

$\underline{\bigstar\:\textsf{According to the given Question :}}$

$:\implies\sf CSA=Circumference\:of\:Base \times Height\\\\\\:\implies\sf CSA = 2\pi r \times h\\\\\\:\implies\sf CSA = 2\pi r \times r\\\\\\:\implies\sf CSA = 2\pi {r}^{2}$

⠀

$\therefore\:\underline{\textsf{Hence, the correct option is d) \textbf{2 \pi\textsf r^\textsf2 }}}.$