Question 24
Quadrilateral $ABCD$ is inscribed in a circle. Points $E$ and $F$ lie on diagonals $BD$ and $AC$, respectively, with $DE=DA$ and $CF=CB$. If $\angle ABD=43^\circ$, find $\angle EFC$ in degrees.
Interpretation: Use the source-solution configuration shown below: A, B, C, D occur in that order around the circle. If P is the intersection of AC and BD, F is strictly between A and P, and E is strictly between P and B.
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.
Interpretation: Use the source-solution configuration shown below: A, B, C, D occur in that order around the circle. If P is the intersection of AC and BD, F is strictly between A and P, and E is strictly between P and B.
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.