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Omni-MATH / Let ABC be a triangle with AB equal{} AC . The angle bisectors of ∠CAB and ∠ABC meet the sides BC and CA at D and E , respectively. Let K be the incentre of triangle ADC. Suppose …

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Let ABC ABC be a triangle with $ AB \equal{} AC$ . The angle bisectors of ∠CAB \angle C AB and ∠ABC \angle AB C meet the sides BC B C and CA C A at D D and E E , respectively. Let K K be the incentre of triangle ADC ADC. Suppose that $ \angle B E K \equal{} 45^\circ$ . Find all possible values of ∠CAB \angle C AB . [i]Jan Vonk, Belgium, Peter Vandendriessche, Belgium and Hojoo Lee, Korea [/i]
Plain-text mathematical notation (without MathML)
Let ABC be a triangle with $ AB \equal{} AC$ . The angle bisectors of ∠CAB and ∠ABC meet the sides BC and CA at D and E , respectively. Let K be the incentre of triangle ADC. Suppose that $ \angle B E K \equal{} 45^\circ$ . Find all possible values of ∠CAB .

[i]Jan Vonk, Belgium, Peter Vandendriessche, Belgium and Hojoo Lee, Korea [/i]
Original LaTeX notation
Let $ ABC$ be a triangle with $ AB \equal{} AC$ . The angle bisectors of $ \angle C AB$ and $ \angle AB C$ meet the sides $ B C$ and $ C A$ at $ D$ and $ E$ , respectively. Let $ K$ be the incentre of triangle $ ADC$. Suppose that $ \angle B E K \equal{} 45^\circ$ . Find all possible values of $ \angle C AB$ .

[i]Jan Vonk, Belgium, Peter Vandendriessche, Belgium and Hojoo Lee, Korea [/i]

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