Answer:
D. 5.4
Explanation:
Using trigonometric ratio
cos 39 = x/7
cross multiple
x = cos39(7)
x=5.4
option D
take 39 degree as reference angle
using cos rule
cos 39 = adjacent / hypotenuse
0.77 = x / 7
x = 7*0.77
x = 5.39
x = 5.4
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