Triangles and Angle Relationships

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.

Tags

CCSS.2.G.A.1

Front

What are the types of triangles based on side lengths?

Back

The types of triangles based on side lengths are: Equilateral (all sides equal), Isosceles (two sides equal), and Scalene (no sides equal).

Tags

CCSS.4.G.A.2

Front

What are the types of triangles based on angles?

Back

The types of triangles based on angles are: Acute (all angles less than 90°), Right (one angle is exactly 90°), and Obtuse (one angle greater than 90°).

Tags

CCSS.4.G.A.2

Front

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

Back

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

Tags

CCSS.8.G.A.5

Front

What is an exterior angle of a triangle?

Back

An exterior angle of a triangle is formed by one side of the triangle and the extension of an adjacent side. It is equal to the sum of the two opposite interior angles.

Tags

CCSS.8.G.A.5

Front

What are remote interior angles?

Back

Remote interior angles are the two interior angles of a triangle that are not adjacent to a given exterior angle.

Tags

CCSS.8.G.A.5

Front

If angle A is 50° and angle B is 60°, what is angle C in triangle ABC?

Back

Angle C = 180° - (50° + 60°) = 70°.

Tags

CCSS.8.G.A.5

Front

What is the relationship between similar triangles?

Back

Similar triangles have the same shape but may differ in size. Their corresponding angles are equal, and their corresponding sides are in proportion.

Tags

CCSS.8.G.A.2

CCSS.HSG.CO.B.6

Front

How do you determine if two triangles are similar?

Back

Two triangles are similar if: 1) Their corresponding angles are equal, or 2) Their corresponding sides are in proportion (AA, SSS, or SAS similarity criteria).

Tags

CCSS.HSG.SRT.A.2

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.