c=bcosB+ccosCc=b \cos B+c \cos Cc=bcosB+ccosC
a=bcosC+ccosBa=b \cos \mathrm{C}+\mathrm{c} \cos \mathrm{B}a=bcosC+ccosB
b=ccosA+acosCb=c \cos A+a \cos Cb=ccosA+acosC
b2=c2+a2−2cacosBb^{2}=c^{2}+a^{2}-2 c a \cos Bb2=c2+a2−2cacosB