Figure ABCD is similar to figure EFGH because the angle measurements are corresponding and congruent. All similar figures will have congruent corresponding angle measurements. The corresponding sides of all similar figures will be proportionate, meaning all sides are in the same ratio (same times as big their corresponding sides). In the figures to the right, each side of the bigger figure is exactly 2 times as big as its corresponding side in the smaller figure.
The figures are in ratio 2:1. This is known as the scale factor.
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