Answers

2015-11-30T20:28:32+05:30
ABCD is a quadrilateral. CE and DE are the bisector of ∠C and ∠D respectively.
 CE is the bisector of ∠C.
 DE is the bisector of ∠D.
 In ΔCED, ∠DCE + ∠CDE + ∠CED = 180° (Angle sum property)
In quadrilateral ABCD,
 ∠A + ∠B + ∠C + ∠D = 360° (Sum of angles of quadrilateral is 360°)
 ∴ ∠A + ∠B + 360° – 2∠CED = 360° [Using (3)]
⇒ ∠A + ∠B = 2 ∠CED
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