Congruent Triangles Exercises

Answer

Let's see what happens if we say that ∠1, ∠2, and ∠3 make up the interior angles of a triangle and both ∠1 and ∠2 are obtuse. Obtuse angles are greater than 90°, so just adding the measures of ∠1 and ∠2 would be greater than 180. That means ∠3 would have to be negative and we can't have negative angles.

Answer

Suppose we have two right angles in a triangle. The sum of two right angles is already 180°. If we use the Angle Sum Theorem, our remaining angle is 0°, which is impossible.

Answer

Yes, equilateral triangles are always isosceles.

Answer

No, isosceles triangles are not always equilateral. Only if all three sides of the isosceles triangle have the same length would it be equilateral.

Answer

The triangle is obtuse and scalene.

Answer

The triangle is equilateral. It could also be described as an acute isosceles triangle, but equilateral is the most accurate description.