The number 13 has long been assocciated with unfortunate incidents. This stems from roman empire rule, and christianity. Pirates considered Friday to be the most unlucky day of the week. At least once a year the two coincide. This is said to be the most unlucky day of the year, but only if you happen to live in Crystal Lake, where Jason Vorhees may murder you.
(n.) A set of mathematical rules that enable one to find the angles of a triangle from one other angle and the length of sides, or vice versa. Operates with the help of sine, cosine and tangent (which are actually ratios, but since kids nowdays have scientific calculators nobody cares), and is used in the real world for measuring the height of a structure without expensive equipment. See also cosine rule and pythagoras' threorum
Trigonometry was the highlight of my day....
Okay, what's the hypotenuse again? And we have the opposite aswell? So what do we use now? Sine, cosine, tangent?