A circular tunnel, 20 m in diameter is blasted through a mountain. A 16 m wide road isto be constructed along the floor of the tunnel. What is the maximum height of the tunnel to the nearest meter?

Answer 1

make a diagram
The road of 16 m will be a chord in your circle.
Draw a line from the centre to the end of the chord, that is a radius of 10.
Now you have a right-angled triangle with sides x and 8 and hypotenuse 10
Use Pythagoras, the rest should be easy