Question 1006326
Making a drawing,  A above, S at bottom at the left, M at bottom to the right, if you want the triangle to be acute, then these two equations  (maybe another one additionally) are necessary:


{{{system(x^2+(x+3)^2<15^2,x^2+15^2<(x+3)^2)}}}
You want the intersection of the solutions to these.


(You would need to simplify that system and solve each inequality, not done/shown in this posting.)