Question 4899
The area of a rectangle is length * width (A=LW)
The area of a triangle is one-half the base * height (A=1/2bh) 
If the triangle area = rectangle area, then
LW=1/2bh 
and if b=w,we can substitute b for w, in the equation:
bw=1/2bh 
divide both sides by b:
w=1/2h 
multiply both sides by 2, to get the answer in terms of the triangle altitude:
2w=h
so the altitude of the triangle is 2 times the altitude of the rectangle.