#5.4 Equilateral and Isosceles Triangles

Front

What is an equilateral triangle?

Back

A triangle with all three sides of equal length and all three angles measuring 60 degrees.

Front

What is an isosceles triangle?

Back

A triangle with at least two sides of equal length and the angles opposite those sides are equal.

Front

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

Back

180 degrees.

Front

If two angles of a triangle are equal, what type of triangle is it?

Back

Isosceles triangle.

Front

What is the formula for finding the area of a triangle?

Back

Area = 1/2 * base * height.

Front

In an isosceles triangle, if the equal sides are 10 cm each and the base is 8 cm, what is the height?

Back

Height = √(10² - (8/2)²) = √(100 - 16) = √84 ≈ 9.17 cm.

Front

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

Back

All angles are equal and each measures 60 degrees.

Front

If the base of an isosceles triangle is 12 cm and the equal sides are 13 cm, what is the height?

Back

Height = √(13² - (12/2)²) = √(169 - 36) = √133 ≈ 11.53 cm.

Front

What is a scalene triangle?

Back

A triangle with all sides of different lengths and all angles of different measures.

Front

How do you determine if a triangle is isosceles using side lengths?

Back

If two side lengths are equal, the triangle is isosceles.