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How do you figure out the area of a circle?

How do you figure out the area of a circle?
If the radius is 7cm then obviously the diameter is 14cm. But I can’t remember to figure out the area of a circle. is it 7*14=98 ?

Area = πr^2
Area = 3.1416(7)^2
Area = 3.1416(49)
Area = 153.93804 sqcm

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8 Responses to “How do you figure out the area of a circle?”

  1. Area = πr^2
    Area = 3.1416(7)^2
    Area = 3.1416(49)
    Area = 153.93804 sqcm
    References :

  2. The area of a circle is

    in terms of raduis Area = (pi)(radius)^2
    in terms of diameter Area = (pi)(diameter)^2/4
    where pi =3.1416

    therefore if your raduis is 7 cm

    Area = 3.1416*7*7 = 153.94 cm2
    References :

  3. the area of a circle is pi r square pi= 22/7 there fore area of the circle is
    22/7 *7*7=22*7154 cm we should alwayas take pi as 22/7 in tems of calculating the area
    References :

  4. The area A of a circle of radius R is given by

    A = Pi*R^2,

    where Pi = 3.14159265…

    (In case you want to know, to derive this expression, you can consider the differential area element in polar coordinates and integrate:

    dA = r dr dt,

    where r is the distance from the origin and t is the angle from, say, the x axis.

    The area of a circle would then be

    A = Int[Int[r,r,0,R],t,0,2*Pi] = [(R^2)/2] [2*Pi] = Pi*R^2,

    as expected.

    Here, Int[f(x),x,a,b] means integrate the function f(x) from a to b.)
    References :

  5. Its:
    pi * r*r

    while pi being a constant of 3.14
    in your case its:

    7*7*3.14=153.8

    Its worth noting that while pi used in calculation is 3.14 there are more numbers after the decimal point. The first 50 of them being: 3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510
    References :

  6. The formula for circle’s area is πr^2
    π = 3.14 or 22/7
    r = radius of the circle
    then thid will be 3.14*(7^2) = 3.14*49
    = 153.86 cm^2
    References :

  7. the formula for a circle’s area is:
    pi multiplied by the square of the circle’s radius or in equation form: A = лr^2 (in square units)
    л = 3.1416 (constant, no unit)
    r = 7 (units of length)
    so A = 153.9384 sq.cm.
    References :

  8. the twice of radius is diameter
    or
    d=r/2
    the formula of the area of the circle which is…

    a=r^2*(pi)———-1

    and the relation is

    a=(d^2/4)*pi——2

    if u want to get the area which r is given
    use number 1 equation…

    use number 2 if d …

    how derive the equation of the circle….

    …in the cylindrical coordinate system has 3 elements, which are the rho(p) the radius, the angle or theta(0) and the height(z)…..

    the line elements of this are dp, pdo and dz

    the volume of the cylinder is triple integrate of pdpdodz
    respected to each values..

    Area o circle= int int int pdpdodz, the dp is from 0 cm to a cm(or other value/arbrituary constant) do is from 0 to 2pi and dz is to 0 to 0 (so cancelled)

    becomes A=pir^2
    References :

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