Atriangle has side lengths 10, 16, and 11. is the triangle acute obtuse or right? explain

If the triangle is "right," then 10^2 + 11^2 = 16^2.  Check this out.  Does 100+121 = 256?  No.  This triangle is not "right."

10, 11 and 16 are quite close to one another, so there is no chance of having a longer side that is much greater than either of the other two sides.  This indicates an "acute" triangle.

Think:  if the side lengths were 10, 11 and 21, then you'd not have a triangle, but would have a straight line.  As soon as the larger side passes 21 you'd have an "obtuse" angle.