Given: Ratio of angles of a triangle = 2 : 3 : 5 Concept: Sum of all three angles of a triangle is 180°. Calculation: Short Trick: Ratio of greatest angle to smallest angle = 5 : 2 Detailed Method: Ratio of angles of a triangle = 2x : 3x : 5x According to the question 2x + 3x + 5x = 180° ⇒ 10x = 180° ⇒ x = 18° Smallest angle is = 2 × 18° = 36° Greatest angle is = 5 × 18° = 90° ∴ Required ratio = 90° : 36° = 5 : 2