Short answer = C) 8/10
Working :
Tan A = 8/6 = Opposite / AdjacentOpposite = 8 units
Adjacent = 6 units
Hypotenuse = [tex]\sqrt{8^{2} + 6^{2} }[/tex]
= [tex]\sqrt{64 + 36 }[/tex]
= [tex]\sqrt{100}[/tex]
= 10 units
Cos B = Adjacent/ Hypotenuse
∴ cos B= 8/10