geometry
Mathematical discipline that studies the relations between points, straight lines, curves, surfaces and volumes.
obtuse angle 
Angle between 90° and 180°.
acute angle 
Angle that is smaller than a right angle (less than 90°).
right angle 
Angle formed by two lines or two perpendicular planes that measures 90°.
perpendicular 
Symbol denoting that a straight line meets another at a right angle.
is not parallel to 
Symbol denoting that two straight lines do not remain at a constant distance from one other.
is parallel to 
Symbol denoting that two straight lines remain at a constant distance from one another.
minute 
Symbol placed in superscript after a number that denotes degrees in sixtieths of a measure.
second 
Symbol placed in superscript after a number that denotes degrees in sixtieths of a minute.
pi 
Constant that represents the ratio of a circle’s circumference to its diameter; its value is approximately 3.1416.
degree 
Symbol placed in superscript after a number to denote the opening of an angle or the length of an arc, or in front of an uppercase letter to identify a scale of measurement.