How High and At What Angle Should Person B Shoot to Hit Person A?

[gen.nutville]

Homework Statement

Person A is shot out of cannon at 100m/s at 30 degrees above the horizontal on top of a 75 meter tall cliff. After 3 seconds, Person B, standing next to the cannon, shoots an arrow at 200m/s at Person A. At what height does the arrow strike person A, and what angle did he fire at?

Homework Equations

X_Ay=75+200 sin⁡(θ) (t-3)+g/2 〖(t-3)〗^2
X_Ax=200 cos⁡(θ) (t-3)
X_By=75+50t+g/2 t^2
X_By=86.6t

The Attempt at a Solution

{(75+200sin(θ)(t-3)+g/2(t-3)^2)^2 + (200cos(θ)(t-3))^2}^1/2 = {(75+50t+g/2 t^2)^2 + (86.6t)^2}^1/2

For some reason I am unable to isolate theta

 

[Doc Al]

Make use of the fact that A and B must have the x and y coordinates when they collide.