Use the Pythagorean theorem to find b .

b = 5

Step-by-step explanation:

We can use the Pythagorean theorem

a^2 + b^2 = c^2 where a and b are the legs and c is the hypotenuse

12^2 + b^2 = 13^2

144+b^2 =169

Subtract 144 from each side

144-144+b^2 = 169-144

b^2 = 25

Take the square root on each side

sqrt(b^2) = sqrt(25)

b = 5

560

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