# Classifying Triangles by Sides and Angles

#### Definitions:

• An acute angle is an angle that measures between 0° and 90°.
• An obtuse angle is an angle that measures between 90° and 180°.
• A right angle is an angle that measures 90°.
• A straight angle is an angle that measures 180°.

1. Use the DESMOS program to create the following triangles:
• Equilateral: a type of triangle in which all three sides are the same length.
• Isosceles: a type of triangle in which two of the sides are the same length.
• Scalene: a type of triangle in which all three sides are different lengths.
• Acute: a type of triangle in which all the three internal angles are acute.
• Right: a type of triangle in which one angle is a right angle.
• Obtuse: a type of triangle in which one internal angle is obtuse.

2. Can you sketch a triangle satisfying both criteria shown in the table below? If yes, do so, if not, explain why not in the space provided. For example, can you sketch an acute triangle that is also scalene?

 Scalene Isosceles Equilateral Acute Triangle Right Triangle Obtuse Triangle

3. Verify your results using  GeoGebra. 