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2.5. How Can See It? Pg. 20 Classify Polygons. 2.5 – How Can I See It?______________ Classify Polygons In this section you will discover the names of the many different polygons and how they are classified. 2.28 –EXTERIOR ANGLE OF TRIANGLES
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2.5 How Can See It? Pg. 20 Classify Polygons
2.5 – How Can I See It?______________ Classify Polygons In this section you will discover the names of the many different polygons and how they are classified.
2.28 –EXTERIOR ANGLE OF TRIANGLES a. Compare the interior and exterior angle of the following triangles at right. What do you notice?
70° 55°
Exterior Angle of a Triangle a d b c c+d = 180 a+b+c = 180 a+b+c = c+d a+b = d
Exterior Angle of a Triangle a d b c Sum of two interior angles equals exterior angle
x 50 + 70 = 120 = x
6(15) + 30 120° 6x + 30 5x + 45 = 45 = x + 30 15 = x
Polygon: 1. Has at least 3 sides 2. No sides overlap 3. No curved sides
Line segment forming the polygon Side: M Q T R S
Point where two sides meet Vertex: M M T Q S T R Q R S
Consecutive Sides: Two sides that share a point, one after the other M Q T R S
Segment that joins two nonconsecutive sides Diagonal: M Q T R S
triangle quadrilateral pentagon
triangle quadrilateral pentagon hexagon heptagon octagon nonagon decagon 11-gon dodecagon n-gon
Convex: No corners point inside the shape Concave: Not convex! A corner points inside the shape
1. State whether the shape is a polygon. If yes, is it concave or convex? If no, why not? Yes, Concave or Convex OR No, _________________ Curved side
1. State whether the shape is a polygon. If yes, is it concave or convex? If no, why not? Yes, Concave or Convex OR No, _________________
1. State whether the shape is a polygon. If yes, is it concave or convex? If no, why not? Yes, Concave or Convex OR No, _________________
1. State whether the shape is a polygon. If yes, is it concave or convex? If no, why not? Yes, Concave or Convex OR No, ____________________ Overlaps
All angles are congruent All sides AND all angles are congruent All sides are congruent
2. Classify the name of the polygon by the number of sides. Is the polygon equilateral, equiangular, regular, or neither? a. Pentagon Equilateral
b. quadrilateral Regular
c. Octagon Equiangular
d. Heptagon Regular
e. decagon equilateral
f. Hexagon neither
6x + 17 10x – 27 = 4x – 27 = 17 4x = 44 x = 11
x2–6x–16 x2+12x–106 = 18x – 106 =–16 18x = 90 x = 5
x2+2x–2 x2+8 = 8 = 2x – 2 10 = 2x 5 = x