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Geometry. Glossary of terms. Interior angle: Exterior angle: Regular polygon: Irregular polygon : Symmetry. Glossary of terms. Interior angle: An angle on the inside of a shape Exterior angle: An angle on the outside of a shape
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Glossary of terms • Interior angle: • Exterior angle: • Regular polygon: • Irregular polygon: • Symmetry
Glossary of terms • Interior angle: An angle on the inside of a shape • Exterior angle: An angle on the outside of a shape • Regular polygon: A polygon that has all its faces the same shape and size • Irregular polygon: Its faces are different in shape and/or size • Symmetry: A shape that is in proportion and balance
Interior and exterior angles Exterior angle Interior angles
Shapes and Angles Q. What degree of angle does a straight line equal? A. The angles on any straight line add up to 180° Exterior angle Interior angle 90° 90° 90° + 90° = 180° Exterior angle Interior angle 135° 45° 135° + 45° = 180°
Angles on parallel lines • A line that intersects (crosses) parallel lines creates angles. This line is called a transversal • The angles created are either: • Corresponding to each other • Alternate to each other or • Co-interior to each other (co-interior angles add up to 180°)
Parallel lines and angles Corresponding angles = are the same Alternate angles = are the same Co-interior angles = add up to 180°
Remember • The interior and exterior angle always add up to 180° ext int ext ext int int
Angles inside a triangle • The angles inside a triangle also add up to 180° X° + 67° + 33° = 180° X° = 80° x° 33° 67°
Angles inside a square • A square has four 90° angles that add up to 360°
Polygons • Polygons are closed figures that have several line segments and angles(Poly = many; gonia = angle). • Triangles are polygons with three sides. • Quadrilaterals are polygons that have four sides (quattuor = four, lateralis = side).
Some of the quadrilaterals are so special that they have they own names.
Common Polygons • Parallelogramshave their oppositesides parallel. In rectanglesall the angles areright angles.
More common polygons • A square has fourright angles and allsides are equal • Pentagons have 5 sides and 5 angles(pente = five, gonia = angle). regular irregular
Even more common polygons • Hexagons have 6 sides and 6 angles(hex = six). regular regular or Irregular? irregular