A single-slit minimum is accepted only by the checked width-times-sine ledger. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The slit width multiplies a sine marker
The diagram records a slit width and a rational sine marker. The minimum claim is not accepted until their product matches the wavelength ledger.
a=5msinθ=52
Only one sine marker matches the wavelength
Hold the slit width fixed. Neighboring rational sine markers are visible, but only the row whose product equals one wavelength is accepted.
s5m5m5msinθ515253m111accepted010
A single-slit minimum binds width to a sine marker
The sine marker is a rational ledger value, and the minimum is accepted only when width times sine equals one wavelength.