Although it has not been clearly mentioned, it appears that questioner has given the lengths of sides of #color(red)"six"# triangles.
Let these be
#DeltaA-(3, 5, 7)#
#DeltaB-(4.5, 6, 7.5)#
#DeltaC-(6, 8, 9)#
#DeltaD-(1.2, 2.5, 3.1)#
#DeltaE-(8, 15, 17)#
#DeltaF-(14, 19, 21)#
In a right angled triangle say #Delta-(P,Q,R)#, if #R# is the largest side, then #R^2=P^2+Q^2#.
In an acute angled triangle say #Delta-(P,Q,R)#, if #R# is the largest side, then #R^2 < P^2+Q^2#.
In an obtuse angled triangle say #Delta-(P,Q,R)#, if #R# is the largest side, then #R^2 > P^2+Q^2#.
Hence as #7^2 > 3^2+5^2#, #DeltaA# is obtuse angled triangle.
As #7.5^2 = 4.5^2+6^2#, #DeltaB# is right angled triangle.
As #9^2 < 6^2+8^2#, #DeltaC# is acute angled triangle.
As #3.1^2 > 1.2^2+2.5^2#, #DeltaD# is obtuse angled triangle.
As #17^2 = 8^2+15^2#, #DeltaE# is right angled triangle.
As #21^2 > 9^2+14^2#, #DeltaF# is obtuse angled triangle.
