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Angles-Polygons-TrianglesQuadrilaterals
Angles
If two lines cross we say they INTERSECT.
If two lines in the same plane do not
intersect, we say they are PARALLEL.
If two lines make square corners at the point
of intersection we say the lines are
PERPENDICULAR.
Angles made by perpendicular lines are
called RIGHT ANGLES.
Angles continued
Two right angles form a STRAIGHT
ANGLE.
An angle smaller than a right angle is
called an ACUTE ANGLE.
An angle greater than a right angle is
called an OBTUSE ANGLE.
The degree measure of a CIRCLE is 360
degrees.
POLYGONS
Memorize the following (on p. 5):
Triangle
Quadrilateral
Pentagon
Hexagon
Heptagon
Octagon
Nonagon
Decagon
Undedecagon
Dodecagon
3 sides
4 sides
5 sides
6 sides
7 sides
8 sides
9 sides
10 sides
11 sides
12 sides
POLYGONS CONTINUED
If a polygon has an indentation, it is call a
CONCAVE POLYGON.
Any polygon which does not have an
indentation is call a CONVEX POLYGON.
If all sides of a polygon have the same length,
the polygon is EQUILATERAL.
If all angles of a polygon have the same
measure the polygon is EQUIANGULAR.
If the polygon has all sides of the same length
and all angles of the same measure, it is
called a REGULAR POLYGON.
TRIANGLES
The SUM of the THREE ANGLES in any triangle is 180
DEGREES.
If a triangle has a right angle it is called a RIGHT
TRIANGLE.
If all angles of a triangle measure less than 90 degrees,
the triangle is an ACUTE TRIANGLE.
If one angle in a triangle has a measure greater than 90
degrees, the triangle is an OBTUSE TRIANGLE.
If two sides of a triangle have equal length, the triangle
is an ISOSCELES TRIANGLE.
If the lengths of all sides are equal, the triangle is an
EQUILATERAL TRIANGLE.
If all sides have different lengths, the triangle is a
SCALENE TRIANGLE.
Design Fun With Polygons