# Author: Bernat Requena Serra

## Double-Angle Formulas

Select your language EnglishSpanish Let α be an angle. The double-angle (2α) trigonometric ratios can be expressed as a function of the trigonometric ratios of the angle α, that is, the double-angle formulas: Double-Angle...

## Sum and Difference Identities and Formulas

Select your language EnglishSpanish Angle sum and difference identities express trigonometric functions of sums of angles α ± β in terms of functions of α and β. Using the sum and difference formulas allows us to...

## Trigonometric ratios and Trigonometric Functions

Select your language EnglishSpanish Trigonometric ratios are defined as the ratios of the sides of a right triangle. There are six trigonometric ratios in total: sine, cosine, tangent, and their reciprocals, cosecant, secant and...

## Arctangent

Select your language EnglishSpanish The arctangent (notation: arctan or tan-1) is the inverse function of the tangent. That is: As the arctangent and tangent are inverse functions, their composition is the identity. Thus: Properties...

## Arccosine

Select your language EnglishSpanish The arccosine (notation: arccos or cos-1) is the inverse function of the cosine. That is: As the arcsine and sine are inverse functions, their composition is the identity. That is:...

## Arcsine

Select your language EnglishSpanish The arcsine (notation: arcsin or sin-1) is the inverse function of the sine. That is: As the arcsine and sine are inverse functions, their composition is the identity. That is:...

## Cotangent

Select your language EnglishSpanish The cotangent is the reciprocal trigonometric ratio of the tangent. It is the reciprocal or multiplicative inverse of the tangent, that is, tan θ · cotθ = 1. In a right triangle, the cotangent of...

## Cosecant

Select your language EnglishSpanish The cosecant is the reciprocal trigonometric ratio of the sine. It is the reciprocal or multiplicative inverse of the sine, that is, csc θ · sin θ = 1. In a right triangle, the cosecant of...

## Geometry

Select your language EnglishSpanish GEOMETRY What is geometry? Straight line Polygon Triangle Quadrilateral Pentagon Hexagon Heptagon Octagon Conic Section Circle, Semicircle, and Annulus Polyhedron Prism Pyramid Regular polyhedron Surface Area of Revolution Shapes in...

## Secant

Select your language EnglishSpanish The secant is the reciprocal trigonometric ratio of the cosine. It is the reciprocal or multiplicative inverse of the cosine, that is, sec θ · cos θ = 1. In a right triangle, the secant...