The measures of the ángeles of a triangle are in the ratio 5: 6: 7. clássify the triangle

From experience this is an acute triangle. to prove it you would have to use the Law of Cosines to prove each angle is acute.
Each angle would follow the formula:
Angle A = ArcCos((b^2+c^2-a^2)/(2bc))
A = 44.4 degrees
B = 57.1 degrees
C = 90 - A - B = 78.5 degrees