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
|xy| distance distance between points x and y xy | = 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
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Emmanuel Abara Benson

I'm a highly-evolved 21st century human, a lover of knowledge and a Creative Writer amongst other things...
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