How to find the measure of the angle is you have the incenter?

Find the length of cu, the triangles are similar.

The highest point on earth is the peak of mount everest if you climb to the top you would be approximately 29,035 feet above sea level at remembering that amount is 5280 feet percentage of the height of the mountain would you have to climb to reach a point 2 miles above sea level

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?