Question

Triangle DEF has been dilated to form triangle D'E'F'. What is the least amount of information needed to determine if the two triangles are similar?

A) Angle F=F', angle E=E', and segments EC and E'C' are congruent.

B) Segment EC=E'C', segment DF=D'F', and angles E and E' are congruent.

C) Angles E and E' are congruent, and angles F and F' are congruent.

D) Segments DF and D'F' are congruent, and segments EF and E'F' are congruent.

Answer 1

The answer is C. Angles E and E' are congruent, and angles F and F' are congruent.

Explanation:

You only need two corresponding angles to prove that two triangles are similar. A and B are incorrect mainly because there isn't even a point C nor a point C' to begin with and D is incorrect because you do not need segments to prove that two triangles are similar if you have at least two angles.

Answer 2

C. as long as two angles are congruent you know that the third angle is congruent as well which by the AAA theorem means the two triangles are similar