Solid State

The diffraction pattern of crystalline solid gave a peak at $20=60^{\circ}$. What is the distance ( in cm ) between the layers which gave this peak?

( $\lambda$ of $X$-rays is $1.54 \mathring{A}$ ) $\left(\sin 30^{\circ}=0.5, \sin 60^{\circ}=0.866 ; n=1\right)$

(a) $8.89 \times 10^{-8}$