The radius of a circle, defined as the distance from the center to the edge, can be calculated using two formulas: dividing the diameter by two or the circumference by 2π. The plural form of radius is radii, and all radii in a circle are congruent.
Area of a circle is like the area of a rectangle
because the height of a rectangle would be the
radius of a circle and the base would be π x r.
= π x r x r
So the overall formula for the area of a circle is:
π(r^2)
π (Pi)
π aka pi can be calculated by dividing the
circumference and the diameter together
and it should be roughly 3.14
Circumference
The two formulas to calculate the circumference are:
c = π(d) aka π x d
c = 2πr which also means 2 x π x r
Circumference is like the boarder around the circle.
If you were to straighten out the perimeter of the circle
or the boarder, That would be the arc length of the circle.
Press the cool looking circle beside this paragraph and use
it to help you.
Diameter
There are two formulas to find the diameter:
d = 2(r) aka 2 x r
d = c/2
Diameter is a line that cuts the circle into two
equal parts but not necessarily CUT. The line
just shows the two equal parts on the given circle.
Radius
There are two formulas to get the radius:
r = d/2 (diameter in short is (d))
r = c/2π (circumference in short is (c))
Subtopic
The radius is the distance from the center
point to the edge of the circle.
Radius in short form would be (r)
Plural form of radius: Radii
All radii of a given circle are congruent
