"Setting these equal and factoring out the x = 0 root (where the projectile is on the incline) gives a value for x ; the range 0measured along the incline is ?2v2? ?cos2(?+?)? ? g ? ? cos ? ? b) Of the many ways to approach this problem, a convenient way is to use the same sort of trick, involving double angles, as was used to derive the expression for the range along a horizontal incline." . . . .