## Trigonometry Trigonometry, abbreviated as TRIG, is a branch of mathematics that deals with the relations between the sides and angles of plane or spherical triangles.  For other math terms see Algebra and Geometry.

## Trigonometry Terms

### A

• Arccos - The inverse cosine.
• Arccot - The inverse cotangent.
• Arccsc - The inverse cosecant.
• Arcsec - The inverse secant.
• Arcsin - The inverse sine.
• Arctan - The inverse tangent.

### C

• Cosecant (csc, cosec) - The ratio of the hypotenuse over opposite side in a right triangle.
• Cosine (cos) - The ratio of the adjacent side of the hypotenuse in a right triangle.
• Cotangent (cot, ctg) - The ratio of the adjacent side to the oposite in a right triangle.

### H

• Heron's formula  -  A formula for the area of a triangle when the lengths of the three sides are known.
• Hyporenuse - The side of right triangle opposite the right angle, which is the longest side.

### I

• Infinite - Having no boundary.
• Inverse statement  -  Disaliow both the hypohesis and conclusion of the origional statement.

### L

• Law of cosines - An equation relating to cosine of an interior angle and the lengths of the sides of a triangle.
• Law of sines - The ratio of the sine of any angle within any specific triangle and the length for the opposite side is a constant.

### O

• Orthocenter - The point of concurrence of the altitudes of the triangle.
• Orthogonal - Perpendicular to a plane.

### P

• Pythagorean theorem - An equation relating the lengths of the sides of a right triangle.  The sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse.
• Proportional - In a constant ratio.

### R

• Ratio - A constant proportion or two real numbers divided by each other.

### S

• Sine (sin) - The ratio of the length of the opposite side to the length of the hypotenuse.

### T

• Tangent (tan) - The ratio of the opposite side to the adjacent side of a right triangle.
• Tangent line - A line that touches the graph of the function at a single point.
• Tangent of a circle - A line that contacts an arc or circle at only one point.
• Trig functions - sine, cosine, tangent, cosecant, secant, and cotangent

### X

• X-axis - The horizontal axis on a coordinate system.

### Y

• Y-axis - The vertical axis on a coordinate system.

Display #
Title
Arccosecant
Arccosine
Arccotangent
Arcsecant
Arcsine
Arctangent
Cosecant
Cosine
Cotangent
Law of Cosines
Law of Sines
Secant
Sine
Tangent
Trig Function Abbreviations
Trig Function Equations
Trig Functions