Circumference of a circle - derivation
This page describes how to derive the formula for the circumference of a circle.
Recall that the definition of pi (π) is the circumference c of any circle divided by its diameter d. Put as an equation, pi is defined as
π
=
c
d
Rearranging this to solve for c we get
c
=
π
d
The diameter of a circle is twice its radius, so substituting 2r for d
c
=
2
π
r
If you know the area
Recall that the area of a circle is given by
area
=
π
r
2
Solving this for r
r
2
=
a
π
So
r
=
√
a
π
The circumference c of a circle is
c
=
2
π
r
D 80
32/40 *100
Precent proportions
32/x = 40/100
Cross multiply
Minutes. Because you cannot concert minutes to hours.
1 hour= 60 Minutes
2 hours= 120 Minutes
Answer:
90
Step-by-step explanation:
take square root and subtract y2 from y1 and x2 from x1
