The answer to the question is B.
Answer:
13.60 See the note below.
Step-by-step explanation:
Remark
This is just the reverse of the question you just did. This time you are trying to solve for c
Givens
Solution
c^2 = a^2 + b^2 Substitute the givens.
c^2 = 8^2 + 11^2 Expand
c^2 = 64 + 121 Combine the right side by adding
c^2 = 185 Take the square root of both sides.
sqrt(c^2) = sqrt(185) Complete the operation
c = 13.601 Round to the nearest 1/100 th
c = 13.60 Note: the zero must be there or the answer does not show the nearest 1/100 th
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
