Answer: 1.25 cm.
Step-by-step explanation:
Given : Volume of a rectangular prism = [tex]35\ cm^3[/tex]
To find : the height of the triangular cross section (h).
Given: Length=7cm
Width=4cm
Volume of rectangular prism = length x width x height
[tex]\Rightarrow\ 35= 7\times4\times h \\\\\Rightarrow h=\dfrac{35}{28}\\\\\Rightarrow\ h= 1.25\ cm[/tex]
Hence, the height of prism is 1.25 cm.