Question

plz tell me formula of perimeter and area of circle

Answer 1

ᴩᴇʀɪᴍᴇᴛᴇʀ ᴏʀ ᴄɪʀᴄᴜᴍꜰᴇʀᴇɴᴄᴇ ᴏꜰ ᴛʜᴇ ᴄɪʀᴄʟᴇ=
$2\pi \: r$
ᴀʀᴇᴀ ᴏꜰ ᴛʜᴇ ᴄɪʀᴄʟᴇ=
$\pi \: {r}^{2}$

Answer 2

Dimension of a circle is given by either it's radius or diameter.

Diameter is twice the radius:
or D = 2R.
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Perimeter of a circle is given as:

Perimeter = 2πR = πD
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Area of circle is given as:

Area = πR^2 = (πD^2)/4
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For semicircle,

Perimeter = πR + 2R = (π+2)R

Area = (πR^2) / 2
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π is a constant. Its approximate value is taken as 3.142 or 22/7.