posted by Adam .
Why do we write radian measures with a π rather than just give the decimal equivalent? (for example, why not use 1.88 rad instead of 3π/5 rad?)
because there is an exact relationship between π and the circle, thus its angles
e.g. tan 45° = tan π/4 or tan .7854 ( I had to round it off)
set your calculator to radians
tan π.4 = 1
tan .7854 = 1.000003673