The angles of a triangle are in the ratio of 3 : 5 : 7.  The triangle is:

Obtuse angle triangle Acute angle triangle right angle triangle isosceles angle triangle

Acute angle triangle

According to triangle property: ⇒ 3x + 5x + 7x = 180° ⇒ 15x = 180°  ⇒ x = 12° Angles are: 3x = 36°,  5x = 60°,  7x = 84° So, the triangle is acute angle