Using calculator, we find:

(1) `cos(pi/6) = cos 30^"o" =\ 0.8660254`

30° - 60° triangle showing `cos(pi/6) = 0.8660254`.

(2) `sec 4.5 = -4.7439275`

The angle 4.5 radians.

(3) `sec 4.5^"o" = 1.0030922`

The angle 4.5 degrees.

Notice the difference between these last two. Without the degree sign, 4.5 means "4.5 radians". It is important to set your calculator properly before starting these problems.