# Classifying Triangles and Angles of Triangles

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This ppt includes the following topics:-
Classifying Triangles by Sides
Classifying Triangles by Angles
Parts of an Isosceles Triangle
Angle Sum Theorem
Third Angle Theorem
Corollaries
1. Classifying Triangles &
Angles of Triangles
Sections 4-1 & 4-2
2. A triangle is the figure formed by 3
segments joining 3 noncollinear
points. Each of the 3 points is a
vertex. The segments are the sides.
Sides : AB, BC , CA A
Vertices : points A, B, C
C B
3. Classifying Triangles by Sides
Scalene Triangle –
no sides congruent
Isosceles Triangle –
At least 2 sides congruen
Equilateral Triangle –
All sides congruent
4. Classifying Triangles by Angles
700
50 0
Acute – 3 acute angles
600
Right – 1 right angle
400
1200
200 Obtuse – one obtuse angle
600
600 600
Equiangular – all angles congruent
5. Parts of an Isosceles Triangle
vertex angle
leg leg
base
base angles
6. Angle Sum Theorem
The sum of the measures of the
angles of a triangle is 180.
1000
40 0 400
7. Third Angle Theorem
 If2 angles of one triangle are congruent to 2
angles of another triangle, then the third
angles are congruent.
8. Corollaries
statements that can be easily proved using a theorem
 Each angle of an equiangular triangle has
measure 60.
 In a triangle, there an be at most one right
angle or obtuse angle.
 The acute angles of a right triangle are
complementary.
9. Exterior Angle Theorem
The measure of an exterior angle of a
triangle equals the sum of the measures
of the 2 remote interior angles.
Remote interior
350 angles
Exterior 750 400
10. Joke Time
What has wings and solves number
problems?
A mothematician
11. What did one math book say to the
other math book?
Don’t bother me! I’ve got my own
problems!
12. What would a math student say to a
fat parrot?