We will have the following:
First, we will find the supplement of the angle given to determine the internal angle of the triangle that we can use, that is:
C = 180° - 58° => C = 122°
Now, we use the law of cosines to calculate the length of the missing side:
c = sqrt(a^2 + b^2 - 2a*b*cos(122°))
That is:
c = sqrt(74.0^2 + 122.0^2 - 2(74.0)(122.0)cos(122°))
so
c = 172.9977521 meters
so, the measurement of the missing side would be approximately 173 meters.
Now, using the law of sines we find the angle at which he should move towards the truck:
172.9977521 / sin(122°) = 122.0 / sin(x)
So:
sin(x) = 122.0*sin(122°) / 172.9977521
Then:
x = Arcsin(122.0*sin(122°) / 172.9977521)
So:
x = 36.73059875°
So, we finally would have that he must move approximately 173 meters towards the truck at an approximate angle of 36.7°.