Hi, I am trying to figure out what angle to set my speakers to for Dolby Atmos. I have two speakers side by side that are facing the ceiling. The sound they produce travels upwards, reflects off the ceiling and then back to the listener to create a more immersive experience. Normally, if the ceiling was parallel to the ground I could figure out what angle to place the speaker using simple trig identities and formulas but what is confusing me is that my ceiling is pitched at an angle and that is throwing me off. The last time I took a geometry course was around 12 years ago so I'm a little rusty. I attached a picture to show the setup. So far I have determined the height of the walls, the distance between the speakers and the listener. What height the speakers are at, and what height I would like the reflected sound waves to hit the listener, and the angle of the ceiling.

I used tan^-1(x)=9'2"/12' to find the angle x= 18.86 degrees for the ceiling angle. I am looking to determine what the angle should be with the ?. I think I will need a system of equations to set this problem up. Can anyone give me any hints or point me in the right direction? Thanks and happy holidays.

-Matthew