Posted by anna on Monday, March 10, 2008 at 8:51pm.
The grade of a road is 7%. What angle does the road make with the horizontal?
I'm confused!! What is the grade of a road? Thanks for the help!

geometrey  drwls, Monday, March 10, 2008 at 8:58pm
The "grade" is the tangent of the slope angle.
arctan 0.07 = 4.00 degrees
(4 degrees is the angle whose tangent is 0.07) 
geometrey  anna, Monday, March 10, 2008 at 9:04pm
how did u get the 4?

geometrey  anna, Monday, March 10, 2008 at 9:05pm
nevermind my calculator was being stupid. thanks

geometrey  anna, Monday, March 10, 2008 at 9:07pm
sorry one more question. so...
a road climbs at an 8 degree angle with the horizontal. what is the grade of the road?
the answer would be 5? 
geometrey  drwls, Monday, March 10, 2008 at 9:05pm
I used the arctan key of my hand calculator. If you don't have one, you should use a table of trig functions

geometrey  drwls, Tuesday, March 11, 2008 at 8:29am
The answer to your second question is the tangent of 8 degrees. That is 0.1405, for a 14.05% grade.
You don't find many roads that steep. Driveways, maybe.