Congruent Triangles and Triangle Sum Theorem Flashcard

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 degrees.

Front

If two angles of a triangle are 50° and 60°, what is the measure of the third angle?

Back

70° (180° - 50° - 60° = 70°).

Front

What does it mean for two triangles to be congruent?

Back

Two triangles are congruent if they have the same size and shape, meaning their corresponding sides and angles are equal.

Front

What is the notation for congruence?

Back

The notation for congruence is '≅'. For example, ΔABC ≅ ΔDEF means triangle ABC is congruent to triangle DEF.

Front

What are the criteria for triangle congruence?

Back

The criteria for triangle congruence are: SSS (Side-Side-Side), SAS (Side-Angle-Side), ASA (Angle-Side-Angle), AAS (Angle-Angle-Side), and HL (Hypotenuse-Leg for right triangles).

Front

If ΔABC ≅ ΔDEF, what can we say about angle A and angle D?

Back

Angle A is congruent to angle D (∠A ≅ ∠D).

Front

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

Back

To find the measure of a missing angle, subtract the sum of the known angles from 180°. For example, if two angles are 40° and 60°, the missing angle is 180° - (40° + 60°) = 80°.

Front

What is the corresponding side to angle Y in ΔWXY ≅ ΔGIY?

Back

The corresponding side to angle Y is side GI.

Front

If one angle of a triangle is 90°, what type of triangle is it?

Back

It is a right triangle.

Front

What is the relationship between the angles in an isosceles triangle?

Back

In an isosceles triangle, the angles opposite the equal sides are also equal.