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
Answer:

Step-by-step explanation:
Hi there!
<u>What we need to know:</u>
- Linear equations are typically organized in slope-intercept form:
where m is the slope and b is the y-intercept (the value of y when the line crosses the y-axis) - Parallel lines always have the same slope and different y-intercepts
<u>1) Determine the slope (m)</u>

Rearrange this equation into slope-intercept form (this will help us find the slope)
Subtract x from both sides

Divide both sides by -2

Now, we can identify clearly that the slope of the given line is
since it's in the place of m. Because parallel lines always have the same slopes, the line we're currently solving for would therefore have a slope of
as well. Plug this into
:

<u>2) Determine the y-intercept (b)</u>

Plug in the given point (-6,-8)

Add 3 to both sides to isolate b

Therefore, the y-intercept is -5. Plug this back into
:

I hope this helps!
The Tama monorail runs for 18 hours every day.
Answer:
29
/12 or 25
/12 or 2.4166667
Step-by-step explanation:
1/2 + 2/3 + 5/4