# Geometry Symbols

Written by Jerry Ratzlaff. Posted in Nomenclature & Symbols for Engineering, Mathematics, and Science

This is a list of the most common Geometry symbols:

SymbolDefinitionExample
$$\triangle$$ triangle $$\triangle ABC$$
$$\angle$$ angle $$\angle ABC = 60^\circ$$
$$\measuredangle$$ measured angle $$\angle ABC = 60^\circ$$
$$\sphericalangle$$ spherical angle $$\angle AOC = 60^\circ$$
$$^\circ$$ degree 1 circle $$= 360^\circ$$
' arcminute $$1^\circ = 60^\prime$$
" arcsecond $$1'=60^{\prime\prime}$$
$$rad$$ radiant, $$1 \;rad = 180^\circ /\pi \;$$ and $$\;1^\circ = \pi / 180 \;rads$$ $$360^\circ = 2\pi\; rad$$ or about $$57.2958^\circ$$
$$grad$$ gradian, four hundredth (1/400) of a full circle $$360^\circ = 400\; grad$$
$$\overleftrightarrow {AB}$$ infinite line distance
$$\overline {AB}$$ line segment from A to B
$$\overrightarrow {AB}$$ start line at point A
$$\overset{\frown} {AB}$$ arc from A to B
$$|A-B|$$ distance between A and B $$|A-B| = 9$$
$$\parallel$$ parallel to $$\overline {AB} \parallel \overline {XY}$$
$$\nparallel$$ not parallel to $$\overline {AB} \nparallel \overline {XY}$$
$$\perp$$ perpendicular lines $$\overline {AB} \perp \overline {XY}$$
$$\sim$$ similarity $$\triangle ABC \sim \triangle XYZ$$
$$\cong$$ congruent, equivalent in size and shape $$\triangle ABC \cong \triangle XYZ$$
$$\therefore$$ therefore $$a=b\; \therefore\; b=a$$
$$\pi$$ $$\pi = 3.141592654...$$ $$C = \pi \cdot d = 2 \cdot \pi \cdot r$$