Answer
A grade of 3.5% is an angle of $3.15^{\circ}$ which is $0.055~radians$
Work Step by Step
Let $x$ be the grade. Let $y$ be the angle in degrees.
$y = (0.9~x)^{\circ}$
$y = [(0.9)(3.5)]^{\circ}$
$y = 3.15^{\circ}$
Let $z$ be the angle in radians. To convert from grade to radians, we should multiply the grade by $\frac{\pi}{200}$:
$z = (\frac{\pi}{200})~x$
$z = (\frac{\pi}{200})(3.5)$
$z = 0.055~radians$
A grade of 3.5% is an angle of $3.15^{\circ}$ which is $0.055~radians$
