Question

in a cylinder its circumference is 14 centimetre and height is 5 centimetre then find its curved surface area and total surface area.​

Answer 1

ANSWER

Given : A Right circular cylinder 

Height =14cm

curved surface area (CSA)=704sq.cm

Volume = ? 

We know, 

Curved surface area of cylinder =2πrh

704cm2=2πr×14cm

r=2π×14704cm

r=14π352cm

r=7π176cm (putting π=722)

r=7×22176×7cm

Answer 2

Given -

• Circumference of the cylinder = 14cm
• Height of the cylinder = 5cm

To find -

• Curved surface area (C. S. A) of cylinder
• Total surface area(T. S. A) of cylinder

Solution -

We know that,

$Circumference \: of \: cylinder = 2\pi \: r$

Putting the values,

$14 = 2 \times \frac{22}{7} \times r$

$14 = \frac{44}{7} \times r$

$r = 14 \times \frac{7}{44}$

$r = \frac{49}{22}$

Now,

$C. S. A \: of \: cylinder = 2\pi \: rh$

$C. S. A \: of \: cylinder = 2 \times \frac{22}{7} \times \frac{49}{22} \times 5$

$C. S. A \: of \: cylinder = 70$

And,

$T. S. A \: of \: cylinder = 2\pi \: r(r + h)$

$T. S. A \: of \: cylinder = 2 \times \frac{22}{7} \times \frac{49}{22} ( \frac{49}{22} + 5)$

$T. S. A\: of \: cylinder = 14( \frac{49 + 110}{22} )$

$T. S. A \: of \: cylinder = 14 \times \frac{159}{22}$

$T. S. A \: of \: cylinder = \frac{2226}{22}$

$T. S. A \: of \: cylinder = 101.2(approx)$

Therefore Curved surface area of the cylinder is 70cm² and total surface area of the cylinder is 101.2 cm²