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Geometry and Trigonometry Difficulty: Medium

In triangle D E F , the measure of angle D is 47° and the measure of angle E is 97°. In triangle R S T , the measure of angle R is 47° and the measure of angle S is 97°. Which of the following additional pieces of information is needed to determine whether triangle D E F is similar to triangle R S T ?

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Explanation

Choice D is correct. When two angles of one triangle are congruent to two angles of another triangle, the triangles are similar. It's given that in triangle DEF, the measure of angle D is 47° and the measure of angle E is 97°. It's also given that in triangle RST, the measure of angle R is 47° and the measure of angle S is 97°. It follows that angle D is congruent to angle R and that angle E is congruent to angle S. Therefore, triangle DEF is similar to triangle RST and no additional information is needed.

Choice A is incorrect and may result from conceptual errors.

Choice B is incorrect and may result from conceptual errors.

Choice C is incorrect and may result from conceptual errors.