1.
The positive acute angle formed between the terminal side of an angle and the x-axis.
2.
The part of a function that dictates the exact correspondence between the elements of one set and the elements of another set.
3.
The circle whose center is at the origin and whose radius is one.
4.
The trigonometric function that is equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse.
5.
The trigonometric function that is equal to the ratio of the side opposite a given angle (in a right triangle) to the hypotenuse.
6.
The ratio of the hypotenuse to the shorter side adjacent to an acute angle (in a right-angled triangle); the reciprocal of a cosine.
7.
The ratio of the hypotenuse (in a right-angled triangle) to the side opposite an acute angle; the reciprocal of sine.
8.
The trigonometric function that is equal to the ratio of the sides (other than the hypotenuse) opposite and adjacent to an angle in a right triangle.
9.
(In a right-angled triangle) the ratio of the side (other than the hypotenuse) adjacent to a particular acute angle to the side opposite the angle.
10.
An operation that assigns a correspondence from elements of one set to elements of another set.
