Mathematics

Problem

Points

A, B, C

and

D

are in a plane such that

AB

subtends an angle of

38^{\circ}

C

and also

38^{\circ}

D

, with

C

and

D

on the same side of

AB

. Which of the following conclusions is correct? a)

AB\,\text{ is a diameter of the circle through } A\,\text{ and } B

AC = AD

A, B, C\,\text{ and } D\,\text{ are concyclic}

\triangle ABC \cong \triangle ABD