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Prove that if angle C = angle D, then angle A = angle E.

 

https://homework.russianschool.com/resource?key=54101jiop7nbb

 

 Apr 12, 2020
 #1
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Since DBE and CBA are straight lines, angle(DBA) = angle(CBE) because they are vertical angles.

 

Somce there are 180o in every triangle:

     angle(D) + angle(A) + angle(DBA)  =  180o  =  angle(C) + angle(E) + angle(CBE)

            angle(D) + angle(A) + angle(DBA)  =  angle(C) + angle(E) + angle(CBE)

                              angle(A)                         =                    angle(E)         (by sutbraction)

 Apr 12, 2020

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