Florida Teacher Certification Examinations (FTCE) Subject Area Practice Test

If a triangle has one angle that is 60 degrees, how is the triangle classified?

1. Isosceles

2. Equilateral

3. Scalene

4. Right-angled

The correct answer is: Scalene

To classify a triangle based on its angles, it is essential to understand the definitions of the different types. A triangle is classified as isosceles if it has at least two equal angles, equilateral if all three angles are equal (each measuring 60 degrees), scalene if all three angles are different, and right-angled if one of the angles measures exactly 90 degrees. Given that one angle measures 60 degrees, the classification can vary depending on the measures of the other two angles. If the other two angles are different and do not equal 60 degrees, then the triangle would indeed be classified as scalene, as all angles would be unique. This aligns with your answer. However, it’s also possible for a triangle to be isosceles if two angles measure 60 degrees, leaving the third angle less than 60 degrees, thus making it not scalene. For it to be equilateral, all three angles must be equal. Since the question only specifies one angle as 60 degrees, we cannot confirm the triangle being equilateral without knowledge of the other angles. In summary, with just one angle at 60 degrees and without additional information about the other angles, the triangle can be classified as scalene if