Materials Science and Engineering: An Introduction

Since we are given that it is a tetrahedral shape, we can solve for delta 0. Delta 0 = 180-90-tan$\frac{1}{\sqrt 2}$ = 180 - 90 - 35.2 = 54.7. However this is only half the angle. Therefore, we must mutiply it by two to get the whole angle. 2 $\times$ 54.7 = 109.4 degrees