$\cos{3\theta} \,=\, 4\cos^3{\theta}-3\cos{\theta}$

$4\cos^3{\theta}-3\cos{\theta} \,=\, \cos{3\theta}$

It is called cos triple angle identity and used as a formula in two various cases.

- Cos of triple angle is expanded as the subtraction of three times cos of angle from four times cos cubed of angle.
- The subtraction of three times cos of angle from four times cos cubed of angle is simplified as cos of triple angle.

Cosine of triple angle identity is used to either expand or simplify the triple angle cos functions like $\cos{3x}$, $\cos{3A}$, $\cos{3\alpha}$ and etc. For example,

$(1) \,\,\,\,\,\,$ $\cos{3x} \,=\, 4\cos^3{x}-3\cos{x}$

$(2) \,\,\,\,\,\,$ $\cos{3A} \,=\, 4\cos^3{A}-3\cos{A}$

$(3) \,\,\,\,\,\,$ $\cos{3\alpha} \,=\, 4\cos^3{\alpha}-3\cos{\alpha}$

Learn how to derive the rule of cos triple angle identity by geometric approach in trigonometry.

Latest Math Topics

May 21, 2023

May 16, 2023

May 10, 2023

May 03, 2023

Latest Math Problems

May 09, 2023

A best free mathematics education website that helps students, teachers and researchers.

Learn each topic of the mathematics easily with understandable proofs and visual animation graphics.

A math help place with list of solved problems with answers and worksheets on every concept for your practice.

Copyright © 2012 - 2022 Math Doubts, All Rights Reserved