SOLUTION: A farmer has a field in the shape of right angled triangle with legs (sides other than the hypotenuse) of lengths 16 m and 8 m. She wants to leave a space in the form of a square

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Question 986115: A farmer has a field in the shape of right angled triangle with legs (sides other than the hypotenuse) of lengths 16 m and 8 m. She wants to leave a space in the form of a square of largest area for growing wheat and remaining area for growing vegetables. Find the length of the side of such a square

Answer by ikleyn(52780) About Me  (Show Source):
You can put this solution on YOUR website!

We are given a right-angled triangle  ABC  (see the Figure)  with the legs  |AB| = 8  and  |AC| = 16.                   
A square  ADEF  is inscribed to the triangle  ABC  in such a way that the triangle and
the square have the common right angle  LA.
We need to find the length of the square side.

Let x be the square side length.
Then the length of the segment  DB  is  8 - x  and the length of the segment  CF  is  16 - x.

The triangles  DELTADBE  and  DELTAFEC  are right angled triangles.
They have congruent acute angles  LFCE  and  LDEB  as these angles are the corresponding
angles at the parallel lines  AC  and  DE  and the transverse  BC.

Hence, the triangles  DELTADBE  and  DELTAFEC  are similar right-angled triangles.
Therefore,  their legs are proportional:



        Figure

abs%28CF%29%2Fabs%28FE%29 = abs%28ED%29%2Fabs%28DB%29,     or     %2816-x%29%2Fx = x%2F%288-x%29.                        (3)

Now we need to solve the last equation for the unknown  x.  Simplify the equation  (3)  step by step:

%2816-x%29%2A%288-x%29 = x%5E2,

16%2A8+-+16x+-+8x+%2B+x%5E2 = x%5E2,

128+-+24x+%2B+x%5E2 = x%5E2,

24x = 128,   x = 128%2F24 = 16%2F3 = 51%2F3.

Answer.  The side measure of the square is of  51%2F3  m long.

For a similar problem see the lesson  Miscellaneous problems on similar triangles  in this site.