GED Math Practice Test

If triangle ABC is similar to triangle DEF, what can be said about the relationship between angle A and angle D?

1. Angle A equals angle D

2. Angle A is greater than angle D

3. Angle A is less than angle D

4. Angle A is not related to angle D

The correct answer is: Angle A equals angle D

When two triangles, such as triangle ABC and triangle DEF, are similar, they share proportional relationships in their corresponding angles and side lengths. This means that all corresponding angles in similar triangles are equal in measure. Therefore, angle A in triangle ABC is equal to angle D in triangle DEF. The property of similarity indicates that if two triangles are similar, not only are their angles equal, but the ratios of the lengths of the corresponding sides are also constant. This fundamental concept is key in various geometric applications, making it essential for understanding the broader implications of triangle similarity in mathematics. Given that angle A is equivalent to angle D, this reinforces the relationship intrinsic to similar triangles, underlining the significance of this relationship in geometric proofs and problems. Other choices do not accurately express this specific relationship, as they suggest inequalities or a lack of correspondence, which is not applicable in the context of similar triangles.