So...we know the adjacent side and we're looking for the opposite side...looks like we need to use the tangent function here...so we have
tan (32) = (x-2.2) / 15 ......note that Bob's line of sight is 2.2 m "up" the pole, so (x-2.2) will represent the rest of the pole length with "x" being the height ... so we have
15 tan(32) = x - 2.2 add 2.2 to each side
2.2 + 15 tan(32) = x = 11.57 m