+128408 This one is a little tough....
Connect WY .....since WX = XY then angles WYX and and YWX = 45°
So WY is the hypotenuse of triangle WXY and the side opposite the hypotenuse (WY) =
sqrt [ 4^2 + 4^2] = sqrt [ 32]
Now angle WYZ in the other triangle formed = (135 - 45 ) = 90°
So....triangle WYZ is also right with WZ = the hypotenuse and ZY and WY the legs
So
YZ = sqrt [WZ^2 - WY^2 ] = sqrt [9^2 - (sqrt (32)^2 ] = sqrt [ 81 - 32] = sqrt [ 49] = 7 = "a"
