Law o cosines
In trigonometry, the law o cosines (an aa kent as the cosine formula or cosine rule) relates the lenths o the sides o a triangle tae the cosine o ane o its angles. Uisin notation as in Fig. 1, the law o cosines states
whaur γ denotes the angle conteened atween sides o lenths a an b an opposite the side o lenth c.