VTMO 2015 — Grade 8 — final Question 3

$x = \frac{b^{2} + c^{2} - a^{2}}{2 bc} , y = \frac{a^{2} - \left(b - c\right)^{2}}{\left(b + c\right)^{2} - a^{2}}$. Find $P = x + y + xy$.