A point is a location in the plane with no dimensions, represented as a dot and denoted by a capital letter A, B, P, ...[br]If two points are proven to be in the same location, they are the same point.

[b]A[/b], [b]B[/b], and [b]C[/b] are points in the plane.[br][math]A_1[/math] and [math]B_1[/math] are connected by the vector [math]A_1B_1[/math][br][b]O[/b] is the centre of the circle with radius [b]OP[/b][br]

[b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI2.html]Definition[/url] [/b]A [i]line[/i] is breadthless length.[br][b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI3.html]Definition[/url] [/b]The ends of a line are points.[br][b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI4.html]Definition[/url] [/b]A [i]straight line[/i] is a line which lies evenly with the points on itself.[br][br]We will refer to a ``line'' in this work, we mean a straight-line[br]A line is a straight, one-dimensional object that extends infinitely in both directions. It has no thickness and is determined by any two distinct points on it. A line is denoted by two capital letters sometimes shown with a line above them, e.g., AB, CD, OP, ...

[b]AB [/b]is a line segment, a portion of a line with two endpoints.[br][b]CD [/b]is an infinite line, extending indefinitely in both directions.[br][b]EF [/b]is a vector, a directed line segment from point E to point F.[br][b]OP [/b]is a radius, a line segment from the center O to a point P on the circle.

[b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI15.html]Definition[/url] [/b]A [i]circle[/i] is a plane figure contained by one line such that all the straight lines falling upon it from one point among those lying within the figure equal one another.[br][b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI15.html]Definition[/url] [/b]And the point is called the [i]center[/i] of the circle.[br][b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI15.html]Definition[/url] [/b]A [i]diameter[/i] of the circle is any straight line drawn through the center and terminated in both directions by the circumference of the circle, and such a straight line also bisects the circle.[br][br]A circle is a circumference, all points of the circumference are equal radii from the center[br]The distance from the center to the circle is called the radius.[br]A circle is denoted by the symbol ⊙ followed by its center, [br]e.g., ⊙AB, or ⊙(O,P) where OP is the radius of the circle and O is the center of the circle

⊙AB, is a floating circle where AB is the radius of the circle and A is the center of the circle [br]⊙(O,P) is defined by the line OP. Where OP is the radius and O is the center of the circle[br]⊙(C,D) is defined by Vector CD, where CD is the radius and C is the center of the circle

[b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI10.html]Definition[/url] [/b]When a straight line standing on a straight line makes the adjacent angles equal to one another, each of the equal angles is [i]right,[/i] and the straight line standing on the other is called a [i]perpendicular[/i] to that on which it stands.[br][br]Perpendicular lines are two lines that intersect at a right angle (90 degrees). Perpendicular lines are denoted by the symbol ⊥, e.g., AB⊥CD.

Line AB is perpendicular to line CD[br]The space is split into 4 angles of equal size. [br]∠ AED = ∠ DEB = ∠ BEC = ∠ AEC [br]All Angles are 90 degrees

[b][url=https://mathcs.clarku.edu/~djoyce/java/elements/bookI/defI23.html]Definition[/url] [/b][i]Parallel[/i] straight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction.[br][br]Parallel lines are two or more lines in the same plane that never intersect, no matter how far they are extended in either direction. Parallel lines are denoted by the symbol ∥, e.g., AB∥CD