Trigonometry

2. The reciprocal of the cosine function.
3. formulae, A Formulas that express trigonometric functions of multiple angles in terms of trigonometric functions of single angles.
5. An operation that assigns a correspondence from elements of one set to elements of another set.
6. of cosines, A law that relates the sides of a triangle to the cosine of one of its angles.
8. The ratio of the length of the adjacent side to the length of the hypotenuse in a right-angled triangle.
12. The reciprocal of the tangent function.
13. The part of a function that dictates the exact correspondence between the elements of one set and the elements of another set.
16. trigonometric functions, A functions that determine the angle of a right-angled triangle when the lengths of the sides are known.
17. function, A function that repeats itself in regular intervals.
18. functions, There are six trigonometric functions: Sine, cosine, tangent, cosecant, secant, and cotangent.
20. The reciprocal of the sine function.

1. The set of all possible inputs of a function.
4. theorem, A theorem that states that in a right-angled triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides.
7. The ratio of the length of the side opposite a given angle to the length of the hypotenuse in a right-angled triangle.
9. The set of all possible outputs of a function.
10. The ratio of the length of the side opposite a given angle to the length of the adjacent side in a right-angled triangle.
11. angle, The positive acute angle formed between the terminal side of an angle and the x-axis.
14. circle, The circle whose center is at the origin and whose radius is one.
15. The repeating interval of a periodic function.
19. of sines, A law that relates the sides of a triangle to the sines of its angles.