Triangle Sum, Inequality, and Hinge Theorem

Front

What is the Triangle Sum Theorem?

Back

The Triangle Sum Theorem states that the sum of the interior angles of a triangle is always 180°.

Front

What is the Hinge Theorem?

Back

The Hinge Theorem states that if two triangles have two pairs of equal sides, the triangle with the larger included angle will have a longer third side.

Front

What is the Triangle Inequality Theorem?

Back

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

Front

How do you find the measure of a missing angle in a triangle?

Back

To find a missing angle, subtract the sum of the known angles from 180°.

Front

What type of triangle has one angle greater than 90°?

Back

An obtuse triangle has one angle greater than 90°.

Front

What type of triangle has all sides of different lengths?

Back

A scalene triangle has all sides of different lengths.

Front

What is an isosceles triangle?

Back

An isosceles triangle has at least two sides that are equal in length.

Front

What is an acute triangle?

Back

An acute triangle has all angles less than 90°.

Front

If two angles of a triangle are 45° and 55°, what is the measure of the third angle?

Back

The third angle measures 80° (180° - 45° - 55° = 80°).

Front

How do you classify a triangle with angles measuring 60°, 60°, and 60°?

Back

It is classified as an equilateral triangle, as all sides and angles are equal.