Answer:
Obtuse triangle.
Step-by-step explanation:
Side a = 5
Side b = 2
Side c = 4
Angle ∠A = 108.21° = 108°12'36" = 1.88862 rad
Angle ∠B = 22.332° = 22°19'54" = 0.38976 rad
Angle ∠C = 49.458° = 49°27'30" = 0.86321 rad
Since one angle is above 90 degrees, the triangle is obtuse triangle.
This cannot be an acute triangle.