Use similar ratios. 5/4=x/6. Use cross multiplication. 30=4x. Divide by 4 to get x by itself. x=7.5 THIS IS NOT THE ANSWER!! This is the entire side length. Subtract 6 from this to get x. 7.5-6=1.5. x=1.5
The shape of the cross-section formed is a triangle, when a cone is cut in such a way that the cross-section is perpendicular to the base and it passes through the vertex.