we can use pythagorean theorem to solve this ... since we have a and c, we can use c^2 - a^2 = b^2
12^2 - 6^2 = b^2
144 - 36 = b^2
180 = b^2 (now we get the square root of each side)
√108 = √b² (108 can be written as 36 times 3)
√36 √3 = √b²
6√3 = b
so, your answer is 6√3...B
