Remark
The question is an application of the Tangent Function.
Tan(63) = Opposite / Adjacent
Givens
Opposite side = height of the tree = 50 feet.
Adjacent side = shadow length which we have to solve for.
Solution
Tan(63) = opposite/ Adjacent Add a 1 on the left so you have a proportion.
Tan(63)/ 1 = 60 / adjacent Cross multiply
Adjacent * Tan(63) = 1 * 60
Adjacent = 60 / tan(63)
Adjacent = 60 / 1.963
Adjacent = 30.57 feet.