How do you find out the law of cosine angle of the hip, ankle and knee? MCQ 23:51 Biomechanics How do you find out the law of cosine angle of the hip, ankle and knee? 1) Use sqrt ((Xp-Xd)^2+(Yp-Yd)^2) to find each side of the angle you are looking for. 2) use law of cosine equation cos^-1 (a^2-b^2-c^2)/-2bc) Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+