The cross-section of a tunnel is a circular arc. The maximum height of the tunnel is 10 (units). A vertical strut 9 (units) high supports the roof of the tunnel from a point 27 (units) along the ground from the side. Calculate the width of the tunnel at ground level. Please help me solve this. P.S:-I'd post this in HW help, but this isn't my home work, its just a sum thats bugging me.