1.

In the given figure,the side BC of ∆ABC has been produced to a point D.If the bisectors of ∠ABC and ∠ACD meet a point E then prove that ∠BEC =½ ∠BAC.​

Answer»

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\huge{\underline{\underline{\sf{\orange{Question:-}}}}}

In the given figure,the side BC of ∆ABC has been produced to a POINT D.If the bisectors of ∠ABC and ∠ACD meet a point E then PROVE that ∠BEC =½ ∠BAC.

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Side BC of ∆ABC has been produced to D.

∴ ∠ACD = ∠BAC + ∠ABC

⇒  \frac{1}{2} \angle \: ACD =  \frac{1}{2} \angle \: bAC \:  +  \frac{1}{2} \angle \: ABC \\

⇒ \angle \: ECD =   \frac{1}{2}  =\angle \: BAC +  \frac{1}{2} \angle \: ABC.  \:  \:  \:  \:  \:  \:  \:  \: ....(i)\\

Again,side BC of ∆EBC has been produced to D.

\therefore \: \angle \: ECD = \angle \: CBE + \angle \: BEC

⇒ \angle \: ECD =  \frac{1}{2} \angle \: ABC + \angle \: BEC. \:  \:  \:  \:  \:  \:  \: ...(ii) \\

From (i) and (ii), we GET

\frac{1}{2} \angle \: ABC + \angle \: bEC =  \frac{1}{2} \angle \: BAC +  \frac{1}{2} \angle \: ABC \\  \\  \:  \:  \:  \:  \:  \:  \:  \: (each \: equal \: to \: \angle \: ECD).

\therefore \: \angle \: BEC =  \frac{1}{2} \angle \: BAC.

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