The skateboard ramp rises from the ground at an angle of 30 degrees. The ramp covers 20 feet on the ground. Let the length of the inclined surface of the ramp be L.

Using the angle of incline and the distance covered on the ground gives:

cos 30 = 20/L

=> L = 20/cos 30

=> L = `20/(sqrt 3/2)`

=> L = `20*2/sqrt 3`

=> L = `40/sqrt 3`

=> L = 23.094

**The length of incline is 23.094 feet.**