2* h+n+cos(β) = k+λ$$2\cdot h+n+cos(\beta)$$ = $$k+\lambda$$

2* h = k+λ-n-cos(β)$$2\cdot h$$ = $$k+\lambda-n-cos(\beta)$$

h = $$h$$ = $$\frac{k+\lambda-n-cos(\beta)}{2}$$ 
h = 0.5* k+ 0.5* λ- 0.5* n- 0.5* cos(β)$$h$$ = $$0.5\cdot k+0.5\cdot \lambda-0.5\cdot n-0.5\cdot cos(\beta)$$
