Vai su: http://www.WolframAlpha.com e cerca:
contour line
period
(seleziona "math definition")
periodic function
periodic sequence
frequency
Herz
circular functions
sine
(seleziona "math function" e "referring to a...")
cosine
(seleziona "math function" e "referring to a...")
tangent
(seleziona "math function" e "referring to a...")
sin
cos
tan
mathworld subject trigonometric functions
pi
pi to 1000 digits
vector
(seleziona "referring to ..." e "general topic")
scalar multiplication
unit vector
direction
protractor
compass
arc
polar coordinates
mathworld subject computation aids
mathworld subject vector algebra
vector multiplication
 ALTRO