The law of this function states that, for a triangle ABC, c squared equals a squared plus b squared minus 2 a b times this function of the angle C. One over this function of x is the secant of x.
A hyperbolic form of this function is defined for a variable x as one-half times quantity e to the x plus e to the minus x. The law of this function states that, for a triangle ABC, c squared equals a squared plus b squared minus 2 a b times this function of the angle C. One over this function of x is the secant of x. For 10 points, name this function equal to the length of the adjacent side over that of the hypotenuse.
A hyperbolic form of this function is defined for a variable x as one-half times quantity e to the x plus e to the minus x.
cosine