It is 1 : 1 Solution: In $\triangle\text{ABC}$ $\text{AB = AC}$ $\therefore \angle\text{ABC} = \angle\text{ACB}$ (angles opposite to equal sides of a triangle are equal) ...(1) In $\triangle\text{DBC},$ $\text{DB = DC},$ $\therefore \angle\text{DBC} = \angle\text{DCB}$ (angles opposite to equal sides of a triangle are equal) ...(2) subtract 2 from 1 $\angle\text{ABC}-\angle\text{DBC} = \angle\text{ACB}-\angle\text{DCB}$ (equals subtracted from equals gives equal) $= \angle\text{ABD} = \angle\text{ACD}$ Divide both the sides by $\triangle\text{ACD}$ $\Rightarrow\frac{\angle\text{ABD}}{\angle\text{ACD}}=1$ $\therefore \angle\text{ABD} : \angle\text{ACD}=1:1$
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