Question 1178411
*[illustration trough.png].

 Volume of the trough = area of triangle * length

3500 = 130 *area of triangular section

3500/130=26.9 cm^2

area of triangular section 26.9= 1/2 l^2

l^2=53.8
l=7.33
sin 45 deg = h/7.33

h= 7.66/sqrt(2)
h=5.4