Explain why a straight line on graph shows a constant rate change.

  QR = 28 inches or 44 inches

Step-by-step explanation:

In right triangle QNP, the length of QN is given by the Pythagorean theorem as ...

  QP² = QN² +PN²

  QN = √(QP² -PN²) = √(1521 -225) = √1296 = 36

In right triangle RNP, the length of RN is similarly found:

  RN = √(RP² -PN²) = √(289 -225) = √64 = 8

So, we have N on line QR with QN = 36 and RN = 8.

If N is between Q and R, then ...

  QR = QN +NR = 36 +8 = 44

If R is between Q and N, then ...

  QR = QN -NR = 36 -8 = 28

The possible lengths of QR are 28 in and 44 in.