Answer: D) 53.74
This value is approximate.
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Work Shown:
x = length of AB
Use the sine rule to say
sin(angle) = opposite/hypotenuse
sin(B) = AC/AB
sin(61) = 47/x
x*sin(61) = 47
x = 47/sin(61)
x = 53.7376 ..... make sure your calculator is in degree mode
x = 53.74
So AB = 53.74 approximately