The derivative of this function is equal to the negative sine of x, and this function's namesake law is a generalization of the Pythagorean Theorem for non-right triangles.
This function can be written as the quantity e to the i theta plus e to the negative i theta all divided by two, and its hyperbolic type equals one half times the quantity e to the x plus e to the negative x. This function's Taylor series expansion begins 1 minus x squared over 2 factorial plus x to the fourth over 4 factorial. The derivative of this function is equal to the negative sine of x, and this function's namesake law is a generalization of the Pythagorean Theorem for non-right triangles. For 10 points, name this function, which is defined for a right triangle as the adjacent leg over the hypotenuse.
This function can be written as the quantity e to the i theta plus e to the negative i theta all divided by two, and its hyperbolic type equals one half times the quantity e to the x plus e to the negative x.
Cosine