What are the definitions and classifications of triangles based on their angles?

Here are the solutions to the triangle problems.

Question 11.
Define the term triangle.

• Definition: A triangle is a polygon with three straight sides and three vertices (corners). The sum of its three interior angles always equals $180^\circ$.

Question 12.
Classify the following triangles with angles.

• a) $60^\circ, 60^\circ, 60^\circ$

  • All three angles are equal.
  • Classification: Equilateral triangle (and also equiangular).

• b) $70^\circ, 40^\circ, 70^\circ$

  • Two angles are equal ($70