Draw line theta from left to right intersections and ya got two triangles.
Pythagoras gets you the length of that line. Trig gets you the two remaining angles of the red triangle (sohcahtoa!!)
180-angles gets you one angle of the new triangle.
You have to assume its an oblique triangle so make a perpendicular from x to get two right triangles, and then use some algebra on the lengths that you know and don’t know. Then trig again gets you cos theta = x/length and you get the remaining angles. Maybe I left a step out but generally thats the process.
You sure?
Draw line theta from left to right intersections and ya got two triangles. Pythagoras gets you the length of that line. Trig gets you the two remaining angles of the red triangle (sohcahtoa!!) 180-angles gets you one angle of the new triangle.
You have to assume its an oblique triangle so make a perpendicular from x to get two right triangles, and then use some algebra on the lengths that you know and don’t know. Then trig again gets you cos theta = x/length and you get the remaining angles. Maybe I left a step out but generally thats the process.