# Tagged: trigonometry

## 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...

## 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...

## Tangent

Select your language EnglishSpanish In a right triangle, the tangent of an angle θ is defined as the ratio of the opposite leg (a) to the adjacent leg (c). It is one of the...