in right angled triangle $ABC$ ,A contains the right angle.
let $AD$ be the altitude from $A$ to $BC$.
now,draw perendiculars from $D$ to $AB$ and $AC$ respectively $DE$,$DF$
perpendicular projection from $E,F$ are $EM,FN$ on $BC$.
show that,altitude $AD=EM+FN$
source:-gogeometry website
the altitude value of r8angle triangle
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