Exploring Isosceles and Equilateral Triangle Properties

Mr. Wolf's geometry lesson covers isosceles and equilateral triangles, explaining their properties, such as equal sides and angles. The lesson includes theorems about base angles and equilateral triangles, and provides examples of solving for angles and side lengths. It concludes with a demonstration of calculating the perimeter of an isosceles triangle.

What are the two equal sides of an isosceles triangle called?

• Legs

• Angles

• Vertex

• Base

In an isosceles triangle, what is the angle opposite the base called?

• Right angle

• Obtuse angle

• Vertex angle

• Base angle

What is true about the base angles in an isosceles triangle?

• They are always obtuse

• They are always right angles

• They are always congruent

• They are always different

If a triangle is equilateral, what can be said about its angles?

• They are all 90 degrees

• They are all 30 degrees

• They are all 45 degrees

• They are all 60 degrees

Tags

CCSS.4.G.A.2

In an isosceles triangle with legs of equal length, what are the angles adjacent to the base called?

• Obtuse angles

• Right angles

• Base angles

• Vertex angles

Tags

CCSS.HSG.CO.C.11

If the base angles of an isosceles triangle are 65 degrees each, what is the measure of the vertex angle?

• 70 degrees

• 60 degrees

• 50 degrees

• 80 degrees

Tags

CCSS.8.G.A.5

In an equilateral triangle, if one side is 7 units, what is the length of the other sides?

• 7 units

• 6 units

• 8 units

• 5 units

Tags

CCSS.4.G.A.2

In an isosceles triangle, if the base angles are congruent and one leg is 7 units, what is the length of the other leg?

• 8 units

• 7 units

• 6 units

• 5 units

Tags

CCSS.HSG.SRT.B.4

If the equation for the legs of an isosceles triangle is 7x - 1 = 5x + 13, what is the value of x?

• 5

• 6

• 7

• 8

Tags

CCSS.HSG.SRT.B.4

What is the perimeter of an isosceles triangle with legs of 48 units each and a base of 17 units?

• 113 units

• 114 units

• 115 units

• 116 units

Tags

CCSS.3.MD.D.8