Double-angle formulas

Double angle formulas:

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \sin{(2x)} = 2\sin{x}\cos{x} }

$\cos {(2x)}=\cos ^{2}{x}-\sin ^{2}{x}$
Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \;\;\;\;\;\;\;\;\;\;\;\;\; = 2\cos^2{x} - 1 }
Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \;\;\;\;\;\;\;\;\;\;\;\;\; = 1 - 2\sin^2{x} }

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \tan{(2x)} = \frac{2\tan{x}}{1 - \tan^2{x}} }

Resources