#### 7equestrian7

##### New member

1. The motion of a particle is given by x=-2t[SUP]2 [/SUP]and y=t[SUP]3[/SUP]-3t+9, t

__>__0. Find the coordinates of the particle when its instantaneous direction of motion is horizontal.

I know the answer is (-2, 7) but I'm not quite sure how to get there. I have started by finding dx/dt= -4t and dx/dy= 3t[SUP]2[/SUP]-3, but unsure of where to go from here.

2. The motion of a particle is given by x=lntand y=t[SUP]2[/SUP]-4t. Find the coordinates of the particle when its instantaneous direction of motion is horizontal.

I know the answer is (ln2, -4) but I'm not quite sure how to get there. I have started by finding dx/dt= 1/t and dy/dt= 2t-4, but unsure of where to go from here.