Question

Wendy described four triangles as shown below: Triangle A: All sides have length 9 cm. Triangle B: Two sides have length 10 cm, and the included angle measures 60°. Triangle C: Two angles measure 50°. Triangle D: Base has length 8 cm, and base angles measure 45°. Which triangle is not a unique triangle? Triangle A Triangle B Triangle C Triangle D

Answer 1

The first one

Explanation:

because all of the sides have the same measurement.

Answer 2

Triangle C

Explanation:

Triangle A: All sides have length 9 cm.

By SSS this is a unique triangle.

Triangle B: Two sides have length 10 cm, and the included angle measures 60°.

By SAS this is a unique triangle.

Triangle C: Two angles measure 50°.

This gives us at most SS Similarity, so we do not have a unique triangle. The triangle sides can be any length. This is not unique.

Triangle D: Base has length 8 cm, and base angles measure 45°. Which triangle is not a unique triangle?

This gives us ASA, so we have a unique triangle.

Answer: Triangle C