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Geometry To Know
Study the major geometry terms you need to know.
Question | Answer |
---|---|
a one dimensional figure that extends forever in both directions | line |
part of a line, with two endpoints | segment |
a point at the end of a line segment or ray | endpoint |
a part of a line that has one endpoint and extends forever in the other direction | ray |
to cross through the same point | intersect |
two lines that cross (intersect) at right angles | perpendicular |
two lines, segments, or rays that do not cross, no matter how far they extend | parallel |
two rays with the same endpoint | angle |
each of the rays forming an angle | side |
the common endpoint of two rays forming an angle | vertex |
a unit of angle measure ( 1/360 of a complete circle), represented with (°) | degree |
a tool that measures angles | protractor |
an angle that measures 90°, it forms a perfect corner | right angle |
an angle smaller than a right angle | acute angle |
an angle greater than a right angle but smaller than a straight angle (between 90° and 180°) | obtuse angle |
an angle formed by two rays pointing in opposite directions (180° angle) | straight angle |
two angles whose measures add up to 90°; they make a Corner | complimentary angles |
two angles whose measures add up to 180°; they make a Straight line | supplementary angles |
angles with the exact same measure | congruent angles |
a closed figure made of line segments | polygon |
a closed figure made from three line segments | triangle |
The sum of the angles in a triangle must equal | 180 degrees |
a triangle with three acute angles (all angles < 90°) | acute triangle |
a triangle with an obtuse angle (one angle > 90°) | obtuse angle |
a triangle with a right angle (one angle=90°) | right angle |
the longest side of a right triangle (the side opposite the right angle) | hypotenuse |
either of the two sides in a right triangle that form the right angle | leg (of a right triangle) |
a triangle with three sides of the same length | equilateral triangle |
a triangle with at least two sides of the same length | isosceles triangle |
a triangle with no sides of equal length | scalene triangle |
a polygon whose sides and angles have equal measures | regular polygon |
a polygon that does NOT have all sides and angles equal | irregular polygon |
two polygons with the exact same shape but of different size | congruent polygons |
a closed figure made from 4 line segments | quadrilateral |
a closed figure made from 5 line segments | pentagon |
a closed figure made from 6 line segments | hexagon |
a closed figure made from 7 line segments | heptagon |
a closed figure made from 8 line segments | octagon |
a closed figure made from 9 line segments | nonagon |
a closed figure made from 10 line segments | decagon |
The sum of the angles in a quadrilateral must equal | 360 degrees |
a quadrilateral with exactly two sides parallel | trapezoid |
a quadrilateral whose opposite sides are parallel and equal | parallelogram |
a parallelogram with all sides the same length (irregular quadrilateral, parallelogram) | rhombus |
a parallelogram with opposite sides the same length and all angles measuring 90° (irregular quadrilateral, parallelogram) | rectangle |
a parallelogram with all sides the same length and all angles measuring 90°(regular quadrilateral, parallelogram, rhombus) | square |
a set of points that are a given distance from a center point | circle |
the distance around the outside of a circle | circumference |
a line segment from the center of the circle to any point on the circle | radius |
a line segment whose endpoints are on a circle | chord |
a line segment connecting two points on a circle and passing through the center (a special kind of chord) | diameter |
a flat surface that extends forever in all directions | plane |
a location on a plane with no length, no width, and no depth | point |
a set of lines used to locate points on a plane | coordinate plane |
vertical axis (up & down) | y-axis |
horizontal axis (across) | x-axis |
always read the ____-axis first | X |
a pair of numbers used to locate a point on a coordinate plane (x,y) | ordered pair(coordinates) |