Two vectors, x and y form a right angle. vector x is 48 inches long and vector y is 14 inches long. the length of the resultant vector is

First Photo - This is the problem drawn into the paper. If you have two vectors and they form a right angle (90°) between them, the Resultant Vector will appear like this, from the right angle.

Obs.:
1 - VR = Resultant Vector;
2 - The angle formed by the VR and the two vectors ISN'T a bisector.

Second Photo - You can move the bottom extremity of the Y vector to the arrow of the X vector and the tips from the Y and VR vectors will meet, forming a Right Triangle, whose the VR is the Hypotenuse (Opposes the right angle / Larger Side).

Now you just put the values in the Pythagorean Theorem:

Where VR is the "a".