Help with uncertainty percentage

[GreenMan39]

Homework Statement

Determine the percent uncertainty in theta and in sin theta when theta equals 20.0 + or - 0.5 degrees?
delta theta/theta = ?
delta sin theta/ sin theta = ?

Homework Equations

Percent uncertainty is a ratio of the uncertainty to the measured value.
%uncertainty = uncertainty/measured

The Attempt at a Solution

I'm not sure exactly how to solve it. I know that in some cases you would find each deviation, average the two values, and then divide the difference between the average and one deviation by the average. I'm just not sure how to apply that to this problem.

theta 1 = 20.5
theta 2 = 19.5
theta average = 20

 

[GreenMan39]

Is it the difference between max and min values, divided by average, multiplied by 100?
(20.5-19.5)/20*100= 5%
and sin(20.5)-sin(19.5)/((sin20.5 + sin19.5)/2)*100