Answer:
3 root 7
Step-by-step explanation:
h^2 = b^2 + a^2
12 square = b square + 9 square
144 = b^2 + 81
144-81 = b^2
63 = b^2
b = root of 63
b = root 7 x root 9 ................( since 7x9=63)
b = 3 root 7 ..............( since root of 9 is 3)
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