there is 12 inches in a foot. and if the tree grows 4 inches every year, then in 3 years the tree would be 1 foot. 13 x 3 = 39, thus proving that in 39 years, it will be 13 feet tall. I may be wrong but this sounds correct.
Answer: Like the angles BAC (56°) and BDC has the same arc BC in the circumference, these angles must be congruent, then angle BDC must be equal to 56°.
