Here's how to find the correct answer.
Your looking for "Length DE"
Here's what information you already have
mDE or The degree measure. This is 36
r or your radius. This is 10 cm
Now here is the formula you use to solve the problem:
Length DE = ( mDE / 360 ) ( 2 * pi * r )
Now lets use all the information we have and solve the problem.
1) Write out your formula Length DE = ( mDE / 360 ) ( 2 * pi * r )
2) Plug in what you already know Length DE = ( 36 / 360 ) ( 2 * pi * 10 )
3) 36 / 360 = 0.1 take this decimal and turn it into a fraction
4) Convert 0.1 to a fraction (steps on how to do that below)
4.1) Put your decimal into a fraction divided by 1 0.1 / 1
4.2) Multiply the top and bottom by 100 10 / 100
4.3) Simplify the fraction 1 / 10
5) Simplify the second part of the formula ( 2 * pi * 10 ) = ( 20 * pi )
6) Rewrite the formula Length DE = ( 1/10 ) ( 20 * pi )
7) Leave pi out and solve Length DE = ( 1/ 10 ) * (20)
Length DE = 2
8) Replace pi Length DE = 2 * pi
9) Multiply together 2 * pi = 6.283185307
10) Round the decimal to the nearest Length DE = 6.3
There you have it the answer is B. 6.3