Calculation: vOwALX - 1

 2* h* n* cos(β)  = 
 
 ( 2* k+1)* λ
/ 2
 2* h* n* cos(β) =  
 ( 2* k+1)* λ
/ 2
$$2\cdot h\cdot n\cdot cos(\beta)$$ = $$\frac{(2\cdot k+1)\cdot \lambda}{2}$$
 2* h* n* cos(β) =  k* λ+ 
 λ
/ 2
$$2\cdot h\cdot n\cdot cos(\beta)$$ = $$k\cdot \lambda+\frac{\lambda}{2}$$
h =  
 ( k* λ+ 
 λ
/ 2
)
/ 2/ n/ cos(β)
$$h$$ = $$\frac{k\cdot \lambda+\frac{\lambda}{2}}{2\cdot n\cdot cos(\beta)}$$
h =  
 0.5* λ* ( 2* k+1)
/ 2/ n/ cos(β)
$$h$$ = $$\frac{0.5\cdot \lambda\cdot (2\cdot k+1)}{2\cdot n\cdot cos(\beta)}$$
h =  
 0.25* λ* ( 2* k+1)
/ n/ cos(β)
$$h$$ = $$\frac{0.25\cdot \lambda\cdot (2\cdot k+1)}{n\cdot cos(\beta)}$$
h =  
 0.5* k* λ
/ cos(β)/ n
+ 
 0.25* λ
/ cos(β)/ n
$$h$$ = $$\frac{0.5\cdot k\cdot \lambda}{cos(\beta)\cdot n}+\frac{0.25\cdot \lambda}{cos(\beta)\cdot n}$$