Art of Problem Solving
AoPS Online
Math texts, online classes, and more
for students in grades 5-12.
Visit AoPS Online ‚
Books for Grades 5-12 Online Courses
Beast Academy
Engaging math books and online learning
for students ages 6-13.
Visit Beast Academy ‚
Books for Ages 6-13 Beast Academy Online
AoPS Academy
Small live classes for advanced math
and language arts learners in grades 2-12.
Visit AoPS Academy ‚
Find a Physical Campus Visit the Virtual Campus

Difference between revisions of "Double angle identities"

m (Wording)
m (→‎Proof)
 
Line 8: Line 8:
  
 
== Proof ==
 
== Proof ==
−
Please Try to prove it on your own.
+
Please try to prove it on your own.
  
 
== See Also ==
 
== See Also ==
 
* [[Trigonometric identities]]
 
* [[Trigonometric identities]]

Latest revision as of 15:12, 14 February 2025

The trigonometric double-angle identities are easily derived from the angle addition formulas by just letting $x = y$. Doing so yields:

  • $\sin (2x) = 2\sin (x) \cos (x)$
  • $\cos (2x) = \cos^2 (x) - \sin^2 (x)$
  • $\tan (2x) = \frac{2\tan (x)}{1-\tan^2 (x)}$

This article is a stub. Help us out by expanding it.

Proof

Please try to prove it on your own.

See Also

Retrieved from "https://artofproblemsolving.com/wiki/index.php?title=Double_angle_identities&oldid=242557"