Calculating Error In Wavelength

Homework Statement

I am unsure whether I am calculating the error correctly for the wavelength
given that x=14.3,15.3,16.2,17.1,23.3 all in degrees

Homework Equations

$$\lambda=d*Sin(x)$$

where d is my slit size in meters $$\frac {1}{600000}$$
x=measured angle
$$\delta x= 0.1 degrees$$

The Attempt at a Solution

$$\delta\lambda= \frac {|Cos(x)|\delta x}{600000}$$

Now with my given x's they would produce a different error each time is that right or how do I get an over all error?