Acute Angles
less than 90 degrees
Obtuse angles
greater than 90 degrees
right angles
are 90 degrees
line
endless straight path with no endpoints - has arrows at the ends
line segment
part of a line between two endpoints - has no arrows at ends, only a point
ray
part of a line that has one endpoint and goes on forever in one direction - has an arrow and a point
intersecting lines...
are lines that have only one point in common
a line is perpendicular...
to another if it meets or crosses it at right angles (90�)
regular polygon
a polygon where all sides and angles are the same
how many sides does a triangle have
three sides
how many sides does a quadrilateral have
four sides
how many sides does a pentagon have
five sides
how many sides does a hexagon have
six sides
how many sides does an octagon have
eight sides
what is a congruent figure
same size same shape
what is a similar figure
different size same shape
all regular polygons have the ---- amount of lines of symmetry as they do sides
same
equilateral triangle
all sides are the same
isosceles triangle
two sides are the same
scalene triangle
all sides are different
acute triangles
all angles are acute
obtuse triangle
has exactly one obtuse angle
what does the interior angles of a triangle always equal?
180 degrees
what is a quadrilateral
a polygon with four sides and four angles
trapezoid =
exactly one pair of parallel sides
parallelogram =
2 pairs of congruent sides and 2 pairs of parallel sides
congruent sides are
equal in length
rectangle =
2 pairs of congruent sides and 4 right angles
rhombus =
4 congruent sides and 2 pairs of congruent angles
square =
4 congruent sides and 4 right angles
what does the interior angles of a quadrilateral equal?
360 degrees
why is a square a rectangle?
because it has 4 right angles and opposite sides are equal and parallel
why is a rectangle not a square?
because it has 4 right angles and all four sides are not equal and parallel