Important Geometry Symbols for Math Students

Symbol	Symbol Name	Meaning / definition	Example
∠	angle	formed by two rays	∠ABC = 30°
	measured angle		ABC = 30°
	spherical angle		AOB = 30°
∟	right angle	= 90°	α = 90°
°	degree	1 turn = 360°	α = 60°
deg	degree	1 turn = 360deg	α = 60deg
′	prime	arcminute, 1° = 60′	α = 60°59′
″	double prime	arcsecond, 1′ = 60″	α = 60°59′59″
	line	infinite line
AB	line segment	line from point A to point B
	ray	line that start from point A
	arc	arc from point A to point B	= 60°
⊥	perpendicular	perpendicular lines (90° angle)	AC ⊥ BC
\| \|	parallel	parallel lines	AB \| \| CD
≅	congruent to	equivalence of geometric shapes and size	∆ABC≅ ∆XYZ
~	similarity	same shapes, not same size	∆ABC~ ∆XYZ
Δ	triangle	triangle shape	ΔABC≅ ΔBCD
\|x–y\|	distance	distance between points x and y	\| x–y \| = 5
π	pi constant	π = 3.141592654… is the ratio between the circumference and diameter of a circle	c = π·d = 2·π·r
rad	radians	radians angle unit	360° = 2π rad
^c	radians	radians angle unit	360° = 2π ^c
grad	gradians / gons	grads angle unit	360° = 400 grad
^g	gradians / gons	grads angle unit	360° = 400 ^g