Let AB be a sector of a circle with centre O and radius d, ∠AOB=θ(<π2) , and D be a point on OA such that BD is perpendicular OA. Let E be the midpoint of BD and F be a point on the arc AB such that EF is parallel to OA. Then the ratio of length of the arc AF to the length of the arc AB is

Let AB be a sector of a circle with centre O and radius d, ∠AOB=θ(<

1.	Let AB be a sector of a circle with centre O and radius d, ∠AOB=θ(<π2) , and D be a point on OA such that BD is perpendicular OA. Let E be the midpoint of BD and F be a point on the arc AB such that EF is parallel to OA. Then the ratio of length of the arc AF to the length of the arc AB is
Answer» Let $A B$ be a sector of a circle with centre $O$ and radius $d$ , $∠ A O B = θ (< \frac{π}{2})$ , and $D$ be a point on $O A$ such that $B D$ is perpendicular $O A$ . Let $E$ be the midpoint of $B D$ and $F$ be a point on the arc $A B$ such that $E F$ is parallel to $O A$ . Then the ratio of length of the arc $A F$ to the length of the arc $A B$ is