Three angles of a quadrilateral are equal and the measure of the fourth angle is 120°. Find the measure of each of the equal angles.

Let x be the common angle of quadrilateral.


As per question,


A =B = C = x


D = 120°


As we know that, Sum of all four angles of quadrilateral is 360o.


A + B + C + D = 360°


x + x + x + 120° = 360°


3x = 360° - 120°


3x = 240°


X = 240 / 3


= 80°


A =B = C = 80°


So, Three Angles of quadrilateral whose measuring’s are equal is 80°.


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