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MathsNotations

geometry

Geometry notations

Geometry

\inline xOy The Euclidean plane
\inline  Ox The \inline x-axis of the Euclidean plane
\inline Oy The \inline y-axis of the Euclidean plane
\inline A,\, B,\, C,\, \ldots Points in the Euclidean plane with certain coordinates \inline A(x_A, y_A), \inline B(x_B, y_B), \inline C(x_C, y_C), etc.
\inline  AB The line that passes through points \inline A and \inline B
\inline  A - B - C} This says that the points \inline A, \inline B and \inline C are collinear, i.e. there exists a unique line which passes through all of them.
\inline  [AB] The segment with endpoints \inline A and \inline B
\inline  |AB| The length of the segment with endpoints \inline A and \inline B
\inline  l_1 \parallel l_2 This says that the lines \inline l_1 and \inline l_2 are parallel, i.e. they do not have any points in common.
\inline  l_1 \perp l_2 This says that the lines \inline l_1 and \inline l_2 are perpendicular, i.e. they form a right angle at their point of intersection.
\inline  d(A, B) The distance between the points \inline A and \inline B
\inline  d(A, l) The distance between the point \inline A and the line \inline l
\inline  \angle O, \angle AOB The angle with vertex \inline O and rays \inline OA, \inline OB
\inline  \triangle ABC The triangle with vertices \inline A, \inline B and \inline C
\inline  \triangle ABC \equiv \triangle PQR This says that the triangles \inline \triangle ABC and \inline \triangle PQR are congruent, which means that
|AB| = |PQ| \qquad |AC| = |PR| \qquad |BC| = |QR|.
\inline  \triangle ABC \sim \triangle PQR This says that the triangles \inline \triangle ABC and \inline \triangle PQR are similar, which basically means
\frac{|AB|}{|PQ|} = \frac{|AC|}{|PR|} = \frac{|BC|}{|QR|}.
\inline  [ABCD] The quadrilateral with vertices \inline A, \inline B, \inline C and \inline D
\inline  \mathcal{A}_{\triangle ABC} The area of the triangle \inline \triangle ABC
\inline  \mathcal{A}_{[ABCD]} The area of the quadrilateral \inline [ABCD]
\inline  \mathcal{C}(O, R) The circle with center at the point \inline O and radius equal to \inline R