Geometry notation in LaTeX uses \angle for angles, \triangle for triangles, \perp and \parallel for perpendicular and parallel lines, and \cong and \sim for congruent and similar figures. A bar over two letters marks a segment.
All ways to write it
\angleangle ∠No package needed\measuredanglemeasured angle ∡Package: amssymb\triangletriangle △No package needed\perpperpendicular ⊥No package needed\parallelparallel ∥No package needed\nparallelnot parallel ∦Package: amssymb\congcongruent ≅No package needed\simsimilar ∼No package needed\overline{AB}line segment ABNo package needed\overleftrightarrow{AB}line through A and BPackage: amsmath90^\circdegreesNo package needed
Commands marked with a package need that \usepackage line in a LaTeX document.
Example
\triangle ABC \cong \triangle DEF, \quad \angle ABC = 90^\circ, \quad \overline{AB} \perp \overline{BC}Two congruent triangles, one with a right angle at B.
Questions
How do I write the angle symbol?
\angle prints ∠, so \angle ABC is angle ABC. amssymb adds \measuredangle (∡) and \sphericalangle (∢).
\parallel or \|?
Both print two vertical bars. \parallel is a relation with space around it, right for "line l is parallel to m". \| is a delimiter, used for norms such as \|x\|.
How do I write a degree sign?
Use a superscript circle: 90^\circ. The degree symbol page has the text-mode options and the gensymb package.
Using geometry in Confluence
Confluence Cloud has no built-in LaTeX. With LaTeX Math for Confluence you add a math macro to any page, type \angle and it renders inline or as a block, with a live preview while you edit. Every command on this page renders there without extra packages.