WARM UP

1. What is an Acute Triangle?2. What is an Obtuse Triangle?3. What is a Right Triangle?4. What is a Scalene Triangle?5. What is an Isosceles Triangle?6. What is an Equilateral Triangle?7. Can an Equilateral Triangle also

be an Acute Triangle?

http://www.phschool.com/atschool/academy123/html/bbapplet_wl-problem-431617.html

3.7 Angle-Side Theorems

Theorem 20: If two sides of a triangle are congruent, the angles opposite the sides are congruent.

IF Then

Theorem 21: If two angles of a triangle are congruent, the sides opposite the angles are congruent.

If Then

These are ways to prove an isosceles triangle:

1.Two sides are congruent

2.Two angles are congruent

Markings on a triangle:Smaller side matches opposite <

Medium side opposite med <

Larger side opposite larger <

T. If two sides are not congruent, then the angles opposite are not congruent.

T. If two angles of a triangle are not congruent, their opposite sides are not congruent.

Equilateral and Equiangular are interchangeable in triangles. Not in all shapes!

Rhombus: equilateral but not equiangular

Rectangle: equiangular but not equilateral.

6x-45 15+x

Given: AC>AB

m<B + m<C <180

m<B = 6x – 45

m<C = 15 + x

What are the restrictions on the values of x?

A

B C

m<B > m<C

m<B + m<C <180

You must solve two unknowns.