Question 204865
Remember  that  a 45-45-90 triangle  has  sides  proportional  to  1-1-sqrt2
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sqrt2/15  =  1/ x  ,,,or  x = (15*1)/ sqrt2 = 10.61  units
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checking,  using  pythagorous,  x^2 + x^2 = 15^2,  2 x^2 = 15^, 10.61  ok