Find the geometric mean of 3 and 13

If you answer right ill give brainliest, : )

Aswimming pool is a rectangle with semicircles on the end. the rectangle is 12 meters wide and 30 meters long. the diameter and width of the swimming pool are equal. sketch and label an overhead diagram of the swimming pool. find the area of the swimming pool floor.

Gh bisects fgi. find the measure of hgi •15° •21° •10° •8°