Question 1199998
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In the diagram, Angle A = 40° while BD and CD are the bisectors of
angles EBC and FCB respectively. Find the measure of angle D.
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Thanks!
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The sum of angles ABC and ACB is 180° - 40° = 140°.


The angles EBC and FCB are outer angles of the triangle ABC to angles ABC and ACB, respectively.


Therefore, the sum of angles EBC and FCB is 

    (180°- < ABC) + (180° - < FCB) = 360° - 140° = 220°.


Angles CBD and DCB are halves of angles EBC and FCB;

therefore, < CBD + < DCB = 220°/2 = 110°.


It implies that angle D is  180° - 110° = 70°.    <U>ANSWER</U>


<U>ANSWER</U>.  The angle D measure is 70°.
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Solved.