4.1 Triangles - PowerPoint PPT Presentation

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4.1 Triangles

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A Triangle Is a figure formed by three segments Joining three noncollinear points .it has Sides .. And Angles. Triangles can be classified by sides.. – PowerPoint PPT presentation

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Title: 4.1 Triangles


1
4.1 Triangles Angles
2
A Triangle
  • Is a figure formed by three segments
  • Joining three noncollinear points.it has
  • Sides..
  • And Angles.

3
Triangles can be classified by sides..
  • Scalene (no sides equal)
  • Isosceles (as least 2 sides equal)
  • Equilateral (3 congruent sides)

4
A Triangle can be classified by ANGLES
  • Acute (3 acute angles)
  • Right (1 right angle)
  • Obtuse (1 obtuse angle)
  • Equiangular (3 congruent angles)

5
Triangle Vocabulary
  • Vertex A
  • Vertex B
  • Vertex C

6
Triangle Vocabulary
  • Side opposite angle A
  • Side opposite angle B
  • Side opposite angle C

7
Right Triangles
  • Hypotenuse
  • Leg
  • Leg

8
Isosceles Triangle
  • Base
  • Leg
  • Leg

9
When the sides of a triangle are extended.the
triangle has
  • Interior Angles
  • Exterior Angles

10
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11
Classify the triangle by its SIDES and Angles.
12
Classify the triangle by its SIDES and Angles.
13
Classify the triangle by its SIDES and Angles.
14
Classify the triangle by its SIDES and Angles.
15
Classify the triangle by its SIDES and Angles.
16
Classify the triangle by its SIDES and Angles.
17
Complete each sentence with the word always,
sometimes or never.
18
Click here to explore
19
Click here to explore
20
Theorem 4.1-Triangle Sum Theorem
  • The sum of the interior angles of a triangle is
    180 degrees.

21
What is the measure of the numbered angle?
22
What is the measure of the numbered angle?
23
What is the measure of the numbered angle?
24
Theorem 4.2-Exterior Angle Theorem
  • The measure of an exterior angle of a triangle is
    equal to the sum of the two nonadjacent interior
    angles.

25
A corollary to a theorem
  • Is a statement that can be proved easily using a
    theorem
  • Think of it as a mini-theorem.

26
Corollary to the triangle sum theorem
  • The acute angles of a right triangle are
    complementary.

27
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28
Assignment 4.1
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