Geometry terms
•Point – exact location in space .A
Symbol Point A
•Line – continuous set of points in a straight line path. ( ↔)
Symbol ↔
•Line segment – a line with two end points
Symbol −
•Ray – part of line with one end point.
Symbol →
•Angle is a figure formed by two rays with a common endpoint. The common end point is called the vertex.
Symbol angle B, angle ABC,
•Plane is a flat two-dimensional surface that extends infinitely in all directions. Symbols plane xyz
•Intersecting lines are two lines that cross at exactly one point
•Perpendicular lines are 2 intersecting lines that form a right angle ( 90◦ angle)
•Parallel lines are lines that do not intersect and lie on the same planes.
Angles
•Acute angles are less than 90⁰
•Right angles equal 90⁰
•Obtuse angles are greater than 90⁰ but less than 180⁰.
•Straight angles are equal to 180⁰
•Reflex angles are greater than 180⁰ but less than 360⁰
•Interior points are all points in the plane between the two rays
Angle pairs
•Complementary angles are two angles with a sums of 90⁰
•Supplementary angles are two angles with a sum of 180⁰
•Adjacent angles have a common side and vertex but no common interior points (interior points do not overlap)
•Vertical angles are a pair of opposite angles that are formed by two intersecting lines.
•The sum of all triangle angles are 180⁰
Parallel line and Transversals
•Transversal is a line that intersects two parallel lines.
•Interior angles: angles inside the parallel lines
•Exterior angles: angles outside the parallel lines
•Corresponding angles: angles are congruent ; one interior and one exterior that are nonadjacent; same side of transversal line
•Alternate interior angles: angles are congruent; nonadjacent interior angles on opposite sides of transversal line
•Alternate exterior angles: angles are congruent; nonadjacent exterior angles on opposite sides of transversal line
Polygons
Polygons
•A closed Figure
•Has 3 or more sides
•Each side is a line segment ( they must meet only at their endpoints)
•Regular Polygon all sides and angles are congruent
•Triangle: a polygon having 3 side and 3 vertices
Quadrilaterals
•Square: A quadrilateral with all sides congruent and parallel with 4 right angles
•Rhombus: A quadrilateral with all sides congruent and opposite sides are parallel.
•Rectangle: A quadrilateral with 4 right angles and opposite are congruent and parallel
• Parallelogram: A quadrilateral with opposite sides congruent and parallel
•Trapezoid: A quadrilateral having only one pair of opposite sides parallel
*Kite: A quadrilateral with two pairs of adjacent sides that are congruent.
•Pentagon: 5 side
•Hexagon: 6 sides
•Heptagon: 7 sides
•Octagon: 8 sides
•Nonagon: 9 sides
•Decagon: 10 sides
Triangle
•Acute Triangle : A triangle with each angle less than 90⁰
•Right Triangle: A triangle with one angle that measures exactly 90⁰
•Obtuse Triangle: A triangle with one angle greater than 90⁰
•Equilateral Triangle: A triangle having 3 sides of equal length and 3 angles equal in degrees
•Isosceles Triangle: A triangle having 2 sides equal in length
•Scalene Triangle: A triangle with all 3 sides unequal in length
Circles
*Circle is a set of points in a plane, all of which are the same distance from a given point called the center.
*Radius is a line segment from the center of a circle to a point on the circle [formula of a radius is diameter divided by 2]
*Central angle has its vertex at the center of the circle
*Chord is a line segment with its endpoints on the circle
*Diameter is a chord that passes through the center of a circle [formula of a diameter is 2 times the radius]
*Arc is a part of a circle, with all of its points on the circle
Semicircle is an arc that connects the endpoints of a diameter which measures 180 degrees
Minor Arc is an arc with a measure less than 180 degree
Major Arc is an arc with a measure greater than 180 degree