Triangles Review

Can you identify the type of triangles in

each of the following photos?

Classify each triangle by sides and angles.

It’s an ISOSCELES, ACUTE triangle.

It’s a SCALENE, ACUTE triangle.

It’s an ISOSCELES, RIGHT triangle.

It’s an ISOSCELES, OBTUSE triangle.

It’s an EQUILATERAL, EQUIANGULAR

triangle.

Draw an example of the following triangles, if possible. Mark the diagrams appropriately.

2. Right Equilateral1. Right Isosceles

3. Obtuse Scalene

Not possible!!!!

Isosceles TrianglesGeometry

Unit 5, Lessons 1 & 2

• The sides that are the same length are called legs.

• The other side is called the base.

• An isosceles triangle is a triangle with two congruent sides.

• The angles on each end of the base are called base angles.

• The angle across from the base is called the vertex angle.

Isosceles Triangle Theorem: If two sides of a triangle are congruent, then the angles opposite them are congruent.

I f :

then:

AB AC

B C

Converse of the Isosceles Triangle Theorem: If two angles of a triangle are congruent, then the sides opposite them are congruent.

I f :

then:

B C

AB AC

The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base.

ACD BCD

CD AB

AD BD

Example 1

Find x.

Example 2

Find the measures of 1, 2, 3 and 4.