Question

Macy described four triangles as shown below:

Triangle A: All angles measure 60°.

Triangle B: All sides have length 6 cm.

Triangle C: Two sides have length 6 cm, and the included angle measures 60°.

Triangle D: Base has length 6 cm, and base angles measure 50°.

Which triangle is not a unique triangle?

Triangle A
Triangle B
Triangle C
Triangle D

Answer 1

A all of the sides are the same

Explanation:

Answer 2

Triangle-A is not "unique".
All of its angles are equal (60° each), and all of its sides
have the same length, but that length can be anything ...
1 millimeter, 1 light-year ... anything.

Each of the other choices can only be 1 triangle.
For each one, we can find the size of every angle,
and we can also find the length of every side.