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:
C. 
Step-by-step explanation:
Iterative geometric sequence:
Recursive geometric sequence:
The equations are very similar and you only really need to rearrange it. The factor (2/3) and the first term (9) are given, so you can write the iterative equation:
And so the answer is C.
Answer:
(7w - k)(4x + y)
Step-by-step explanation:
Factor by grouping is best for this expression. To factor by grouping, group pairs of terms with parenthesis. Then find the GCF in each pair. If the parenthesis match after, the factoring is complete.
28xw + 7wy - 4kx - ky
(28xw + 7wy) + (- 4kx - ky)
7w(4x + y) - k (4x + y)
The factors are (7w - k)(4x + y).
Answer:
m∠3 = 64°
Since angle 2 and 3 seem to be complementary angles, we know that the meaning of complementary angles is to add both angles to 90 degrees.
Subtract 90 by the known value to get the value of ∠3
90 - 26 = 64
Answer:
C,. 3 3/4
Step-by-step explanation:
length times with times hight
1 1/4 x 1 1/2 x 2
convert everything to same denominator
1 1/4
1 2/4
1 4/4
solve
1 1/4 x 1 2/4 x 1 4/4
