Question 14An acute isosceles triangle, $ABC,$ is inscribed in a circle. Through $B$ and $C,$ tangents to the circle are drawn, meeting at point $D.$ If $\angle ABC=\angle ACB=2\angle D$ and $x$ is the radian measure of $\angle A,$ then $x=$ $\frac37\pi$$\frac49\pi$$\frac5{11}\pi$$\frac6{13}\pi$$\frac7{15}\pi$
