$\sin (a+b)=\sin (a) \cos (b)+\cos (\alpha) \sin (b)$

$\cos (a+b)=\cos (a) \cos (b)-\sin (a) \sin (b)$

$\tan (\mathrm{a}+\mathrm{b})=[\tan (\mathrm{a})+\tan (\mathrm{b})] /[1-\tan (\mathrm{a}) \tan (\mathrm{b})]$