as you have notice in this graph
we already formed a Triangle shape
That has 3 sides given
If 3 sides of Triangle are given
we can now solve (beta)
by using "Cosine Law"
for us to get (alpha)... we need first the angle (tetha)
by using "Cosine Law"
since we already have the value of (Tetha) which is 120
we can now solve (Alpha)
because 120 and (alpha) are both "Supplementary Angles"
It means the sum of their angles is equal to 180 degrees
in this case, the formula we will use is "Direction Cosine" Formula
