Why is circle 1 similar to circle 2?

Circle 1: center (0, 9) and radius 14
Circle 2: center (0, 9) and radius 7
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A) Circle 1 is a dilation of circle 2 with a scale factor of 2.
.
B) Circle 1 is a dilation of circle 2 with a scale factor of 7.
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C) Circle 1 is a translation of circle 2.
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D) Circle 1 and circle 2 have the same center.

Respuesta :

A) Circle 1 is a dilation of circle 2 with a scale factor of 2.
1/2 = r1/r2 = 14/7 = 2 --> dilation scale factor
aachen

We have a golden rule about similarity of figures. It is "All circle are always similar to each other".

In other words, Every circle is dilated version of another circle. To find the value of dilation, we can find the ratio of its redii.

The ratio of radii of two circles is called the scale factor of dilation between them.

Given are two circles with following information :-

Circle 1: center (0, 9) and radius 14

Circle 2: center (0, 9) and radius 7

Finding the ratio of their radii :-

[tex] \frac{Circle\; 1\; radius}{Circle\; 2\; radius} =\frac{14}{7} = 2 [/tex]

So, scale factor is 2. It means circle 1 is a dilation of circle 2 with a scale factor of 2.

Hence, option A is correct i.e. Circle 1 is a dilation of circle 2 with a scale factor of 2.