Topics in a Trigonometry Course

To learn more about a topic listed below, click the topic name to go to the corresponding MathWorld classroom page.

Cosine	In a right triangle, the ratio of the length of a given angle's adjacent side to the length of the hypotenuse. The cosine function is one of the basic functions encountered in trigonometry (the others being the sine and tangent).
Double-Angle Formulas	A set of formulas that express trigonometric functions of twice an angle in terms of the trigonometric functions of the original angle.
Half-Angle Formulas	A set of formulas that express trigonometric functions of half an angle in terms of the trigonometric functions of the original angle.
Law of Cosines	A formula relating the side lengths and angles of a general triangle. It is a generalization of the Pythagorean theorem.
Law of Sines	For general triangles, a formula relating the ratios of sines of angles to the opposite side lengths.
Sine	In a right triangle, the ratio of the length of a given angle's opposite side to the length of the hypotenuse. The sine function is one of the basic functions encountered in trigonometry (the others being the cosine and tangent).
Tangent	In a right triangle, the ratio of the length of a given angle's opposite side to the length of the angle's adjacent side. The tangent function is one of the basic functions encountered in trigonometry (the others being the cosine and sine).
Trigonometric Addition Formulas	A set of formulas that express trigonometric functions of sums of angles in terms of the trigonometric functions of the original angles.
Trigonometry	The study of angles and of the angular relationships of planar and three-dimensional figures.
Unit Circle	A circle of radius one. MathWorld