The left side can be written as a square. We can take the square root, then subtract 1.
... (x +1)² = 17
... x +1 = ±√17
... x = -1 ±√17
Y= 18 because vertical angles are congruent.
13: 72.25
14: 52
For 14, you need to split the figure into a triangle and rectangle.
