Figure 2. Examples illustrating procedure for defining angles of flexing of body segments and monofin and based on points marked in the axes of joints and tail, in the middle and on the edge of the monofin. A – Angle of flexion in knee joints, B – angle of attack of the monofin’s front part, C- angle of attack of the end part of the monofin, D - angle of attack of the entire surface of the fin.