HG #07: Isosceles and Equilateral Triangles

Front

What is an isosceles triangle?

Back

An isosceles triangle is a triangle that has at least two sides of equal length.

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 to 60°.

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°.

Front

If two angles of a triangle are equal, what can be said about the sides opposite those angles?

Back

The sides opposite the equal angles are also equal in length.

Front

In an isosceles triangle, if the vertex angle is 36°, what are the measures of the base angles?

Back

The base angles are each 72°.

Front

What is the formula for the perimeter of a triangle?

Back

The perimeter of a triangle is the sum of the lengths of its sides: P = a + b + c.

Front

If the perimeter of an isosceles triangle is 77 cm and the equal sides are each 25 cm, what is the length of the base?

Back

The length of the base is 27 cm.

Front

What is the relationship between the sides and angles in an equilateral triangle?

Back

In an equilateral triangle, all sides are equal, and all angles are equal to 60°.

Front

How do you find the length of a side in a triangle if you know the lengths of the other two sides and the angle between them?

Back

You can use the Law of Cosines: c² = a² + b² - 2ab*cos(C).

Front

What is the measure of each angle in an equilateral triangle?

Back

Each angle in an equilateral triangle measures 60°.