Triangle Basics Review

Front

A triangle with at least two sides congruent.

Back

Isosceles Triangle: A triangle that has at least two sides of equal length.

Front

Which of the following CANNOT be the length of the third side if two sides are 4 and 5? (3, 4, 5, 6)

Back

3: The length of the third side must be greater than the difference of the other two sides (1) and less than their sum (9).

Front

Can the lengths 8, 10, and 20 form a triangle? If yes, classify by sides.

Back

No: The sum of the lengths of the two shorter sides (8 + 10 = 18) is less than the length of the longest side (20).

Front

Given two angles of a triangle, 57° and 33°, find the 3rd angle and classify by sides.

Back

90°, Scalene: The third angle is 90° (180° - 57° - 33°) and all sides are of different lengths.

Front

In Triangle ABC, AB = 6, BC = 8, AC = 12. List the angles from largest to smallest.

Back

Front

What is the sum of the interior angles of a triangle?

Back

180°: The sum of the angles in any triangle is always 180°.

Front

Define a scalene triangle.

Back

Scalene Triangle: A triangle with all sides of different lengths.

Front

What is an obtuse triangle?

Back

Obtuse Triangle: A triangle that has one angle greater than 90°.

Front

What is a right triangle?

Back

Right Triangle: A triangle that has one angle equal to 90°.

Front

What is the Triangle Inequality Theorem?

Back

Triangle Inequality Theorem: The sum of the lengths of any two sides of a triangle must be greater than the length of the third side.