Q20 of 46 Page 175

One of the angles of a triangle is equal to the sum of the other two angles. If the ratio of the other two angles of the triangle is 4 : 5, find the angles of the triangle.


Let, the other two angles = 4x and 5x


∴ The biggest angle = 4x + 5x = 9x


According to problem,


⇒ 4x + 5x + 9x = 180


⇒ 18x = 180


⇒ x = 10


∴The angles of the triangle,


4x = 4 × 10° = 40°


5x = 5 × 10° = 50°


9x = 9 × 10° = 90°


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