## What is the legal angle of elevation for a wheelchair ramp?

* "For commercial use when somebody is sitting in the wheelchair or scooter while it climbs the ramp, ADA recommends a 1:12 slope, which means that every 1" of vertical rise requires at least 1’ (12") of ramp length (5 degrees of incline).Example: A 24" rise requires a minimum ramp length of 24’ (288")." (http://www.discountramps.com/wheelchair-ramp-length/a/B20/) *

### A visual representation of this ratio is when the vertical leg of a triangle is 1", and the horizontal one is 12".

### With these measurements, you can find the angle where the hypotenuse meets the longer leg. You do this using the tangent ratio.

Your starting equation would be:

Tan(angle x)= 1/12

When your goal is to find the angle from a ratio, you use the inverse functions. So you would put this equation into your calculator:

Tan^-1=1/12

When you put this into your calculator, you find that the angle is 4.764 degrees, rounded to the nearest thousandth.

# What is the angle of elevation of our ramp?

## We were able to measure both the ramp's hypotenuse and horizontal length. Because we know both of these, we are able to find the angle of elevation through using the Cosine.

### Your original equation would be:

Cos(angle x)=284/298

To find angles, you must use the inverse function. So you would put this equation in your calculator:

Cos(angle x)^-1=284/298

You would then find that the measure of the angle is 17.632 degrees, rounded to the nearest thousandth.

# Does our ramp meet the requirements?

### No! Our ramp is a good 12.868 degrees over the requirement!