
Arc 
arc from point A to point B 
= 60º 
º 
Degree 
1 turn = 360º 
α = 60º 
∠ 
Angle 
formed by two rays 
∠ABC = 30º 

Measured Angle 

ABC = 30º 

Spherical Angle 

AOB = 30º 
∟ 
Right Angle 
= 90º 
α = 90º 
´ 
Arcminute 
1º = 60´ 
α = 60º59' 
´´ 
Arcsecond 
1´ = 60´´ 
α = 60º59'59'' 

Line 
infinite line 

AB 
Line Segment 
line from point A to point B 


Ray 
line that start from point A 

 
Perpendicular 
perpendicular lines (90º 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 
360º = 2π rad 
grad 
Grads 
grads angle unit 
360º = 400 grad 