Which equation can be used to find the unknown length, a, in this triangle?
A right triangle has a side with length 15 meters and hypotenuse with length 17 meters. The other side is labeled a.
A. a squared + 15 squared = 17 squared
B. 15 squared + 17 squared = a squared
C. a squared + 15 = 17 squared
D. a + 15 squared = 17 squared