Flashcard 4-1 Classifying Triangles

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 side lengths?

Back

1. Equilateral Triangle: All sides are equal. 2. Isosceles Triangle: Two sides are equal. 3. Scalene Triangle: All sides are different.

Front

What are the types of triangles based on angles?

Back

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

Front

What is the Triangle Inequality Theorem?

Back

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

Front

Can the side lengths 2, 2, and 4 form a triangle?

Back

No, because 2 + 2 is not greater than 4.

Front

Can the side lengths 4, 7, and 10 form a triangle?

Back

Yes, because 4 + 7 > 10, 4 + 10 > 7, and 7 + 10 > 4.

Front

What does it mean for 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

If ∆ABC ≅ ∆DEF, what can we say about their corresponding angles?

Back

∠A ≅ ∠D, ∠B ≅ ∠E, ∠C ≅ ∠F.

Front

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

Back

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

Front

How do you solve for x in the equation 42 + 8x = 2 + 12x?

Back

Rearranging gives: 42 - 2 = 12x - 8x, so 40 = 4x, thus x = 10.