Half Angle Identities
Half-angle identities for some popular trigonometric functions are,
- Half Angle Formula of Sin,
sin A/2 = ±√[(1 – cos A) / 2]
- Half Angle Formula of Cos,
cos A/2 = ±√[(1 + cos A) / 2]
- Half Angle Formula of Tan,
tan A/2 = ±√[1 – cos A] / [1 + cos A]
tan A/2 = sin A / (1 + cos A)
tan A/2 = (1 – cos A) / sin A
Half Angle Formulas
Half Angle formulas are used to find various values of trigonometric angles such as for 15°, 75°, and others, they are also used to solve various trigonometric problems.
Several trigonometric ratios and identities help in solving problems of trigonometry. The values of trigonometric angles 0°, 30°, 45°, 60°, 90°, and 180° for sin, cos, tan, cosec, sec, and cot are determined using a trigonometry table. Half-angle formulas are widely used in mathematics, let’s learn about them in detail in this article.
Table of Content
- Half-Angle Formulae
- Half Angle Identities
- Half Angle Formulas Derivation Using Double Angle Formulas
- Half-Angle Formula for Cos Derivation
- Half-Angle Formula for Sin Derivation
- Half-Angle Formula for Tan Derivation
- Solved Examples on Half Angle Formulas