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.