Question

the diameter of a circle is 42 cm find its perimeter and area​

Answer 1

Given :

• Diameter of circle = 42 cm.

To find :

• Perimeter of circle.
• Area of circle.

Solution :

• Diameter = 42 cm.

We know ,

${\boxed{\bold{Radius=\dfrac{Diameter}{2}}}}$

$\sf{Radius=\frac{42}{2}\:cm}$

$\implies\sf{Radius=21\:cm}$

✪ Now find the perimeter of the circle.✪

We know,

${\boxed{\bold{Perimeter=2\pi\:r}}}$

$\sf{Perimeter=2\times\frac{22}{7}\times\:21\:cm}$

$\implies\sf{Perimeter=2\times\:22\times\:3\:cm}$

$\implies\sf{Perimeter=132\:cm}$

${\boxed{\green{\sf{Perimeter\: of\: the\: circle\:is\:132\:cm}}}}$

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✪ Now find the area of circle .✪

We know,

${\boxed{\bold{Area=\pi\:r^2}}}$

$\sf{Area=\frac{22}{7}\times\:21\times\:21\:cm^2}$

$\implies\sf{Area=22\times\:21\times\:3\:cm^2}$

$\implies\sf{Area=1386\:cm^2}$

${\boxed{\purple{\sf{Area\: of\: the\: circle\:is\:1386\:cm^2}}}}$

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Answer 2

Diameter = 42 cm

Radius = Diameter / 2

Radius = 42 / 2 = 21 cm

∵ Perimeter = 2πr

$Perimeter=2*\frac{22}{7}*21=44*3=132cm$

∵ Area = πr²

$Area=\frac{22}{7} *21*21\\\\Area=22*3*21=1386cm^2$