Q7 of 34 Page 170

The sum of two angles of a triangle is equal to its third angle. Determine the measure of the third angle.

It is given that the sum of two angles of a triangle is equal to its third angle.


In the given ∆ABC,


Let ∠A + ∠B = ∠C …(1)


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


⇒ ∠A + ∠B + ∠C = 180°


⇒ ∠C + ∠C = 180° {From (1)}


⇒ 2∠C = 180°


⇒ ∠C = 90°


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