Interference pattern, wavelength

[muffintop]

Homework Statement

Suppose the interference pattern shown in the figure is produced by monochromatic light passing through two slits, with a separation of 127 µm, and onto a screen 1.14 m away. What is the wavelength?

Homework Equations

wavelength = (dsin$$\theta$$) / m
y=Ltan$$\theta$$

The Attempt at a Solution

$$\theta$$= arctan (y/L) = arctan (.023 / 1.4) = .941
then plugged it into get wavelenth. i used m = 2 for 2 slits
wavelenth = 127 x 10^-6m x sin .941 / 2

i think I have m wrong?

 

[rl.bhat]

i used m = 2 for 2 slits
m is not the number of slits. It is the order of the fringes starting from m=0 for the central bright fringe.