Triangle or No Triangle

Front

What is a triangle?

Back

A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.

Front

What are the types of triangles based on angles?

Back

1. Acute Triangle: All angles are less than 90°. 2. Right Triangle: One angle is exactly 90°. 3. Obtuse Triangle: One angle is greater than 90°.

Front

What is the sum of the angles in a triangle?

Back

The sum of the interior angles in a triangle is always 180°.

Front

Can a triangle be formed with angles measuring 40°, 80°, and 55°?

Back

No, because the sum of these angles is 175°, which is less than 180°.

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

If two angles of a triangle are 30° and 60°, what is the measure of the third angle?

Back

The third angle is 90° (180° - 30° - 60° = 90°).

Front

What are the conditions for three lengths to form a triangle?

Back

The lengths must satisfy the Triangle Inequality Theorem: a + b > c, a + c > b, and b + c > a.

Front

What is an equilateral triangle?

Back

An equilateral triangle is a triangle in which all three sides are of equal length and all three angles are equal (each measuring 60°).

Front

What is an isosceles triangle?

Back

An isosceles triangle has at least two sides that are equal in length and the angles opposite those sides are equal.

Front

What is a scalene triangle?

Back

A scalene triangle has all sides of different lengths and all angles of different measures.