1. 4-1 Classifying TrianglesB
Side
Angle A C
Vertex

2. Classified by Angles Acute Triangle: all angles are Acute
Obtuse Triangle: 1 angle is Obtuse
Right Triangle: 1 angle is Right (90°)
Obtuse Triangle
Right Triangle
Acute Triangle

3. Equiangular Triangle
An acute triangle with all angles congruent.

4. Classified by Sides Scalene Triangle: No sides are congruent
Isosceles Triangle: 2 sides are congruent
Equilateral Triangle: All 3 sides are congruent.
Scalene
Isosceles
Equilateral

5. Classify each triangle by its Angles and Sides
Right Scalene B
Obtuse Isosceles

6. XY=ZX 2n + 2 = 10 2n = 8 n = 4 XY = 10 YZ = (2(4)) – 2 = 8 – 2 = 6
Find the measures of side XY and YZ of isosceles triangle XYZ if X is the vertex angle (the angle in between the two congruent sides). X
XY=ZX
2n + 2 = 10
2n = 8
n = 4
XY = 10
YZ = (2(4)) – 2
= 8 – 2
= 6
2n + 2 10 Y Z
2n - 2

7. Use the distance formula to find the lengths of each side of the triangle.
Remember the distance formula

8. Try These ~ page 205 #1-6 1. Obtuse 2. Equiangular 3. ABC 4. ACD
5. x = 11, LN = 29, MN = 29
6. x = 5, QR, RS, QS = 25