Formule de calcul prescurtat la trigonometrie

Sin²x+cos²x=1

Tg(ά+β)=tgά+tgβ/1-tgάtgβ

Tg(ά-β)=tgά-tgβ/1+tgάtgβά

Cos(ά+β)=cosάcosβ-sinάsinβ

Cos(ά-β)=cosάcosβ+sinάsinβ

Sin(ά+β)=sinάcosβ-sinβcosά

Sin(ά-β)=sinάcosβ+sinβcosά

Sin2x=2sinxcosx

Cos2x=cos²x-sin²x=2cos²x-1=1-2sin²x

Tg2x=2tgx/1-tg²x

Cos²x/2=1+cosx/2

Sin²x/2=1-cosx/2

Tgx/2=sinx/1+cosx=1-cosx/sinx

Ctgx/2=1+cosx/sinx=sinx/1-cosx 

Sinx=2tgx/2 /1+tg2x/2

Cosx=1-tg2x/2/1+tg2x/2

Sin a +sin b=2sin a+b/2 *cos a-b/2

Sin a cosb=sin(a+b)+sin(a-b)/2

Sin(a+b) +sin(a-b)=2sinacosb