Download Geometry 4.1 Triangle Sum Properties Name: A triangle is a polygon

Geometry
4.1 Triangle Sum Properties
Name: _____________________________
𝐵
A triangle is a polygon with ____________________ sides.
A triangle with vertices 𝐴, 𝐵 and 𝐶 is called “triangle 𝐴𝐵𝐶” or _________________
𝐴
𝐶
Triangles can be classified by their _____________________ or by their ________________________.
Classifying Triangles by Sides
Scalene Triangle
Isosceles Triangle
Equilateral Triangle
_______ Congruent Sides
_______ Congruent Sides
_______ Congruent Sides
Classifying Triangles by Angles
Acute Triangle
Right Triangle
Obtuse Triangle
Equiangular Triangle
Classify the triangles based on their sides AND angles.
1)
________________________
2)
3)
________________________
________________________
Use the figure to classify each triangle by its angle measures
4. DFG
5. DEG
6. EFG
Classify each triangle by its side lengths.
7. EGF
8. DEF
9. DFG
When the sides of a polygon are extended, two types of angles are formed: interior angles and
exterior angles.
Interior angles: Angles inside of the triangle
Exterior Angles: Form ___________________________________ with the interior angles
Interior Angles
Exterior Angles
Triangle Sum Theorem: The sum of the measures of the interior angles of a triangle is _______
𝐵
𝐴
𝐶
Corollary to the Triangle Sum Theorem:
The acute angles of a right triangle are _________________________________
𝐴
𝐵
𝐶
Find the value of 𝒙.
a.
b.
35°
c.
40°
40°
𝑥°
2𝑥 + 5°
Find the side lengths of each triangle.
10.
11.
35°
3𝑥°
4𝑥°