How Wide Is the Slit in a Diffraction Experiment with 450nm Light?

[cassey]

Homework Statement

When 450nm light falls on a slit, the central diffraction peak (central maxima) on a screen 2.0m away is 6cm wide. Calculate the slit width?
wavelength= 450 x 10^9m
L= 2m
y= 0.06m
w=?

Homework Equations

y/L = tantheta = sintheta
sintheta = (m+1/2)lambda / w

The Attempt at a Solution

I attempted at this, and got this answer... can anyone check to see if I did it right?
y/L = sintheta
0.06/2 = 0.03

sintheta = (m+1/2)lambda / w
0.03 = (1+1/2) (450 x 10^-9) / w
w= 2.25 x 10^-5m

 

[blue_leaf77]

sintheta = (m+1/2)lambda / w

You are using a wrong formula. It should be $\sin\theta = m\lambda / w$.