Question 1086764
They are just saying that the angle brace 
where it attaches to the wall and
the end that holds the closet rod makes a
right triangle.
Let the length of the brace = {{{ c }}}
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From where the rod is held by the brace, the
horizontal distance to the wall is {{{ 33 }}} cm
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Fro that point on the wall to where the brace
is attached to the wall = {{{ 17 }}} cm
I can say:
{{{ c^2 = 33^2 + 17^2 }}}
{{{ c^2 = 1089 + 289 }}}
{{{ c^2 = 1378 }}}
{{{ c = 37.121 }}} cm
The brace is 37.121 cm long
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check:
{{{ c^2 = 33^2 + 17^2 }}}
{{{ 37.121^2 = 33^2 + 17^2 }}}
{{{ 1378 = 1089 + 289 }}}
{{{ 1378 = 1378 }}}
OK