Q9 of 34 Page 170

The angles of a triangle are x – 40°, x – 20° and x + 15°. Find the value of x.

It is given that the angles of a triangle are x – 40°, x – 20° and x + 15°.


So, the angles be x – 15°, x and x + 15°


We know that the sum of the angles of a triangle is 180°.


⇒ x – 40° + x – 20° + x + 15° = 180°


⇒ 3x – 45° = 180°


⇒ 3x = 180° + 45°


⇒ x = 75°


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