Mathematics · essential
Double angle formulas for JEE
Trigonometrical identities and trigonometrical functions
Formula
\[\sin 2A=2\sin A\cos A,\\ \cos 2A=\cos^2A-\sin^2A=2\cos^2A-1=1-2\sin^2A,\\ \tan 2A=\dfrac{2\tan A}{1-\tan^2A},\quad \cot 2A=\dfrac{\cot^2A-1}{2\cot A}\]
Variables: \(A\) = angle.
Conditions: For tangent and cotangent, denominators nonzero.
Transformations, equation solving, maxima-minima style simplifications.