Answer: A) 5
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Step-by-step explanation:
Angle B = 90 degrees, and the side opposite this is the hypotenuse AC = 10.
Angle C = 30, and the side opposite this smallest angle is AB. For now we'll call this x.
It turns out that for any 30-60-90 triangle, the hypotenuse is twice as long as the short leg. So if x is the short leg, then 2x is the hypotenuse.
Set 2x equal to the given hypotenuse 10 and solve for x
2x = 10
x = 10/2
x = 5
That makes AB = 5.
In other words, we cut the hypotenuse in half to get the length of the shorter leg.