From Gogeometry
Using :
Define c=AB
S=[ABC]=a.b/2=c.h/2 => a.b=c.h
c=a.b/h => c^2=a^2.b^2/h^2
Pythagoras => a^2+b^2=c^2
=> a^2+b^2=a^2.b^2/h^2
dividing by a^2.b^2 => 1/b^2 + 1/a^2 = 1/h^2
From Gogeometry
Using :
Define c=AB
S=[ABC]=a.b/2=c.h/2 => a.b=c.h
c=a.b/h => c^2=a^2.b^2/h^2
Pythagoras => a^2+b^2=c^2
=> a^2+b^2=a^2.b^2/h^2
dividing by a^2.b^2 => 1/b^2 + 1/a^2 = 1/h^2