Calculation: qXJhyS - 1

cos(α)  = 
 
 ( x1* x2+ y1* y2+ z1* z2)
/ ( saknis( x1^2+ y1^2+ z1^2)* saknis( x2^2+ y2^2+ z2^2))
cos(α) =  
 ( x1* x2+ y1* y2+ z1* z2)
/ ( saknis( x1^2+ y1^2+ z1^2)* saknis( x2^2+ y2^2+ z2^2))
$$cos(\alpha)$$ = $$\frac{x1\cdot x2+y1\cdot y2+z1\cdot z2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}$$
cos(α) =  
 x1* x2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 y1* y2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 z1* z2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
$$cos(\alpha)$$ = $$\frac{x1\cdot x2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{y1\cdot y2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{z1\cdot z2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}$$
α = arccos(( 
 x1* x2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 y1* y2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 z1* z2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
)
)
$$\alpha$$ = $$arccos((\frac{x1\cdot x2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{y1\cdot y2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{z1\cdot z2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}))$$
α = arccos( 
 x1* x2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 y1* y2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
+ 
 z1* z2
/ saknis( x1^2+ y1^2+ z1^2)/ saknis( x2^2+ y2^2+ z2^2)
)
$$\alpha$$ = $$arccos(\frac{x1\cdot x2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{y1\cdot y2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}}+\frac{z1\cdot z2}{\sqrt {x1^{2}+y1^{2}+z1^{2}}\cdot \sqrt {x2^{2}+y2^{2}+z2^{2}}})$$