In the Fig. 5.9, we have

Given: ABC = ACB …(i)


and 4 = 3 …(ii)


According to Euclid’s axiom, if equals are subtracted from equals, then remainders are also equal.


On subtracting Eq. (ii) from (i) ,


We get,


ABC - 4 = ACB - 3


1 = 2


Now, in ABDC, 1 = 2


DC =BD [sides opposite to equal angles are equal]


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