Triangles by TlDmH0mc

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									Triangles
Triangle is a polygon
    with 3 sides.
 Classifications for Triangles
• The angles of a triangle determine one of
  its classifications.

• Acute Triangle has 3 angles less than 90
  degrees each.
• Obtuse Triangle has one angle that is
  greater than 90 degrees.
• Right Triangle has one angle that is
  exactly 90 degrees.
 The other way to classify a triangle is the
 number of sides that are congruent.

Scalene Triangle has no sides congruent.

Isosceles Triangle has 2 sides congruent.

Equilateral Triangle has 3 sides congruent.
• The sum of all three angles
  of any triangle is always 180
  degrees.

• If you know 2 angles, you
  can find the 3rd angle’s
  measure by subtracting their
  total from 180.
Example: 30°, 40°, & ___?
     a + b + c = 180°
  30 + 40 + c = 180°
     70 ° + c = 180°
    -70 °      -70 °
         c = 110°
The angles are 30, 40, 110.
What type of triangle is it?
     Obtuse Triangle
 Example: 90, 20, ____?
        a + b + c = 180°
90 ° + 20 ° + c = 180 °
    110 ° + c ° = 180 °
    -110 °       -110 °
             c = 70 °
The angles are 90, 20, 70.
What type of triangle is it?
     Right Triangle
      Example: x, x, x
  a + b + c = 180
   x + x + x= 180
      3x = 180
        x = 60
The angles are 60, 60, 60.
What type of triangle is it?
   Acute Triangle
     Example: 2x, 3x, x + 30
• Find x, then find each angle.
  2x + 3x + x + 30 = 180
  6x + 30 = 180
     ─ 30 ─ 30
       6x = 150
          x = 25
 2x , 3x ,       x + 30
 50     75        55       Acute Triangle
              Example:
• The sides are 3cm, 4cm, and 5cm.
• This is a Scalene Triangle.


                               5 cm


                      4 cm




                             3 cm
               Example:
• The sides are 18 cm, 10 cm, and 10 cm.
• This is an Isosceles Triangle.

                  10 cm             10 cm




                            18 cm
                   Example:
• All 3 sides are 8 cm.
• This is an Equilateral Triangle.


            8 cm
                                8 cm




                      8 cm
  Every Triangle can be given
       TWO NAMES
One for its              One for its
 angles                    sides

Acute Triangle     Scalene Triangle

Obtuse Triangle    Isosceles Triangle

Right Triangle     Equilateral Triangle

								
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