Answer:
(c) 12.5
Explanation:
You want the unknown leg of a right triangle with one leg 10 and hypotenuse 16.
Sanity check
The triangle inequality tells you the unknown leg of the triangle will have a length between the difference of the two known legs, and the longest leg of the triangle.
Since this is a right triangle, its longest leg is the hypotenuse. The unknown side cannot be longer than that, so must be less than 16.
The difference of the given lengths is ...
16 -10 = 6
so the missing leg must be longer than 6.
Only one answer choice is between 6 and 16: 12.5.
The missing leg length is 12.5 units.
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Additional comment
If you want to figure the length, you can use the Pythagorean theorem:
c² = a² +b²
16² = 10² +b²
b² = 256 -100 = 156
b = √156 ≈ 12.49 ≈ 12.5
The length of the unknown leg is 12.5 units.