Answer:
A) C = 2πr and C' = 2πr' by the definition of circumference.
Step-by-step explanation:
In similar circles, all the linear dimensions, circumference (C) and radius (r), are in the same proportion. Therefore:
[tex]\dfrac{C}{C'}=\dfrac{r}{r'}[/tex]
The formula for the circumference of a circle is C = 2πr. Therefore, the formula for the circumferences of the two circles can be expressed as:
[tex]C = 2\pi r\\\\C' = 2\pi r'[/tex]
Therefore, the first step to prove that two circles are similar is:
[tex]\large\boxed{\textsf{$C = 2\pi r$ and $C' = 2\pi r'$ by the de\;\!finition of circumference.}}[/tex]
