The World Of Triangles

1
The World Of Triangles
2
Triangles

• A triangle is a 3-sided polygon. Every triangle
  has three sides and three angles. When added
  together, the three angles equal 180.

3
Acute Triangles

• A triangle in which all three angles are less
  than 90.

4
Obtuse Triangles

• An obtuse triangle is a triangle in which one of
  the angles is greater than 90.

5
Right Triangles

• A right triangle is triangle with an angle of 90.

6
Scalene Triangles

• A triangle with three unequal sides.

7
Isosceles Triangles

• An isosceles triangle is a triangle with (at
  least) two equal sides.

8
Isosceles Triangle Theorem

• The following movie shows that if two sides of a
  triangle are congruent, then the angles opposite
  those sides are congruent.

9
Equilateral Triangles

• An equilateral triangle is a triangle with all
  three sides of equal length.

10
Equiangular Triangles

• An equiangular triangle is a triangle which has
  three equal angles.

11
Congruent Triangles

• Congruent triangles are triangles whose
  corresponding angles and sides are congruent. 
• They are exactly the same size and shape.

12
The Hypotenuse

• The hypotenuse of a right triangle is the
  triangle's longest side, i.e., the side opposite
  the right angle.

13
The Pythagorean Theorem

• For a right triangle with legs a and b and
  hypotenuse c, a2b2c2.

14
Triangle Quiz

• Please complete the following quiz that covers
  the information that was just presented to you.

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Question 1

• If a triangle has three unequal sides it is a
  ______ triangle.
• A) Scalene
• B) Obtuse
• C) Isosceles

• Answer
• A) Scalene

16
Question 2

• A triangle which has three equal angles is a
  ______ triangle.
• A) Acute
• B) Equilateral
• C) Equiangular

• Answer
• C) Equiangular

17
Question 3

• A triangle with (at least) two equal sides is a
  ______ triangle.
• A) Scalene
• B) Isosceles
• C) Congruent

• Answer
• B) Isosceles

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Question 4

• Two triangles that are equal are called ______
  triangles
• A) Acute
• B) Obtuse
• C) Congruent

• Answer
• C) Congruent

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Question 5

• A triangle with all three sides of equal length
  is a ______ triangle.
• A) Equilateral
• B) Right
• C) Equiangular

• Answer
• A) Equilateral

20
Question 6

• A triangle with an angle of 90 is a ______
  triangle.
• A) Acute
• B) Right
• C) Congruent

• Answer
• B) Right

21
Question 7

• A triangle in which all three angles are less
  than 90 is a ______ triangle.
• A) Right
• B) Acute
• C) Scalene

• Answer
• B) Acute

22
Question 8

• A triangle in which one of the angles is greater
  than 90 is a ______ triangle.
• A) Obtuse
• B) Isosceles
• C) Acute

• Answer
• A) Obtuse

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Question 9

• What is the Hypotenuse of a right triangle?
• A) The smallest angle.
• B) The side opposite the right angle.
• C) The right angle.

• Answer
• B) The side opposite the right angle.

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Question 10

• The Pythagorean Theorem states
• A) pr2
• B) (ab)2/2c
• C) a2b2c2

• Answer
• C) a2b2c2

25
Question 11

• Use the Pythagorean Theorem to solve the
  following
• a 5
• b 12
• c ?

• Answer
• c 13

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