
cosine 
in trigonometry, the ratio between the length of the side next to one of the acute angles in a right triangle and the length of the hypotenuse. 
Pythagorean theorem 
in geometry, the theorem that in a right triangle the square of the hypotenuse is equal to the sum of the squares of the other two sides. 
secant 
a trigonometric function, the reciprocal of the cosine, that for an acute angle is equal to the ratio of the hypotenuse to the side adjacent to the given angle in any right triangle that incorporates the angle. [1/4 definitions] 
sine 
in trigonometry, the ratio, in a right triangle, of the length of a side opposite an acute angle to the length of the hypotenuse. [1/2 definitions] 

