Answer:
C. 7.8
Explanation:
This problem involves the use of a trigonometric ratio. This one specifically involves the use of cosine as it provides the leg adjacent to the angle and the hypotenuse.
cos(40) = 6/x
cos(40)*x=6/x*x
cos(40)*x=6
cos(40)/cos(40)*x=6/cos(40)
x=6/cos(40)
x=7.83
The value of x is C. 7.8