Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2022-part-02 — 197 problems (EN–VI) Question 16

Math Olympiad Vault · MathNet 2022-part-02 — 197 problems (EN–VI)

Question 16

Let $\omega$ be a circle with center $O$ and diameter $AB$. A circle with center $B$ intersects $\omega$ at $C$ and $AB$ at $D$. The line $CD$ intersects $\omega$ at the point $E$ ($E \neq C$). The intersection of lines $OE$ and $BC$ is $F$.

a. Prove that the triangle $OBF$ is isosceles.

b. Find the ratio $\frac{FB}{BD}$, given that $D$ is the midpoint of $OB$.