Let these triangles be #DeltaA-(0.9,1.2,1.5)#; #DeltaB-(7,10,15)#; #DeltaC-(3.1,5.7,7.1)# and #DeltaD-(1,2.4,2.6)#
In a right angled triangle, we should have
sum of the squares of smaller two sides should be equal to the square on the largest side.
In #DeltaA#, we have #0.9^2+1.2^2=0.81+1.44=2.25# and #1.5^2-2.25# - hence #DeltaA# is right angled triangle .
In #DeltaB#, we have #7^2+10^2=49+100=149# and #15^2=225# - hence #DeltaA# is not a right angled triangle. In fact as #149 < 225#, it is an acute angled triangle.
In #DeltaC#, we have #3.1^2+5.7^2=9.61+32.49=42.10# and #7.1^2=50.41# - hence #DeltaC# is not a right angled triangle and as #42.10 < 50.41#, it is an acute angled triangle.
In #DeltaD#, we have #1.2^2+2.4^2=1.44+5.76=7.20# and #2.6^2=6.76# - hence #DeltaD# is not a right angled triangle. In fact as #7.20 > 6.76#, it is an obtuse angled triangle.
