compass

To construct a square equivalent to the sum of two given squares.
Given:  Squares S (ABCD) and S' (EFGH), with sides AD and EH respectively.
Required:  To construct a square, S", equivalent to the sum of squares S and S'.
Procedure:

given squares         establishing side of new square         square of sum

  Use the square command under the sample tools menu of  Custom Tools and construct two squares S (ABCD) and S' (EFGH).  
  Use the straightedge tool and lay off a segment MP.
  Use the perpendicular command under the construct menu and construct a perpendicular at M.
  Use the circle by center + radius command under the construct menu and construct a circle with center at M and radius congruent to segment AD.  Label the intersection of MP and this circle N.
  Use the circle by center + radius command under the construct menu and construct a circle with center at M and radius congruent to segment EH. Label the intersection of this circle and the perpendicular O.
  Use the segment command under the construct menu and construct segment ON. This is the length of a side of the required square.
  Use the straightedge tool and lay off a segment LQ.
  Use the perpendicular command under the construct menu and construct a perpendicular at L.
  Use the circle by center + radius command and construct a circle with center at L and radius congruent to segment ON.  Label the intersection of LQ and this circle I, the intersection of the perpendicular at L and this circle K.
  Use the circle by center + radius command and construct a circle with center at K and radius congruent to segment ON, and another circle with center at I and radius congruent to segment ON.  Label the intersection of these two circles J.
  Quadrilateral S" (IJKL)  is the required square.
  You may choose to construct the interiors of all three squares and then calculate the areas to confirm the sketch.
Proof:
  (MN)^2 + (MO)^2 = (ON)^2  (The square of the hypotenuse of a right triangle is equal to the sum of the squares of the legs.
  S + S' = S"          (Substitution)
Sketch:   Drag either point A or E and check to see if the areas continue to add up.
 
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square equal to sum of two squares

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