Question 1051065
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The altitude of a triangle is 4 meters. Express the base b as a function of the hypotenuse h and state the domain.
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Not enough info,  or incorrect using the terms,  or  doesn't make sense.
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Your formulation is extremely bad.


<pre>
1.  If the triangle is right-angled, then the first phrase must be: "In an right-angled triangle, . . . "


2.  If the triangle is right-angled, then its sides containing the right angle are called "legs". 
    In a right-angled triangle they never are called "base".
    In an right-angled triangle they never are called "altitude".

    In an right-angled triangle the "altitude" is the perpendicular from the vertex drawn to the hypotenuse.
</pre>
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Probably, you are seeking for  b = {{{sqrt(h^2-4^2)}}}.

But with such formulation I can not be confident in anything.