Question 122350
ASSUMING THE 21 INCHES IS THE HYPOTENUSE.
X^2+(2X)^2=21^2
X^2+4X^2=21^2
5X^2=441
X^2=441/5
X^2=88.2
X=SQRT88.2
X=9.3915 INCHES FOR THE SHORT LEG.
2X=2*9.3915=18.783 INCHES FOR THE LONG LEG.
PROOF
9.3915^2+18.783^2=21^2
88.2+352.8=441
441=441