Title: 4.1 Triangles
14.1 Triangles Angles
2A Triangle
- Is a figure formed by three segments
- Joining three noncollinear points.it has
- Sides..
- And Angles.
3Triangles can be classified by sides..
- Scalene (no sides equal)
- Isosceles (as least 2 sides equal)
- Equilateral (3 congruent sides)
4A Triangle can be classified by ANGLES
- Acute (3 acute angles)
- Right (1 right angle)
- Obtuse (1 obtuse angle)
- Equiangular (3 congruent angles)
5Triangle Vocabulary
- Vertex A
- Vertex B
- Vertex C
6Triangle Vocabulary
- Side opposite angle A
- Side opposite angle B
- Side opposite angle C
7Right Triangles
8Isosceles Triangle
9When the sides of a triangle are extended.the
triangle has
- Interior Angles
- Exterior Angles
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11Classify the triangle by its SIDES and Angles.
12Classify the triangle by its SIDES and Angles.
13Classify the triangle by its SIDES and Angles.
14Classify the triangle by its SIDES and Angles.
15Classify the triangle by its SIDES and Angles.
16Classify the triangle by its SIDES and Angles.
17Complete each sentence with the word always,
sometimes or never.
18Click here to explore
19Click here to explore
20Theorem 4.1-Triangle Sum Theorem
- The sum of the interior angles of a triangle is
180 degrees.
21What is the measure of the numbered angle?
22What is the measure of the numbered angle?
23What is the measure of the numbered angle?
24Theorem 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.
25A corollary to a theorem
- Is a statement that can be proved easily using a
theorem - Think of it as a mini-theorem.
26Corollary to the triangle sum theorem
- The acute angles of a right triangle are
complementary.
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28Assignment 4.1