Multiple choice AB is tangent to the circle with centre O at A and $OA=AB$ Find $\angle OAB$. $30^{\circ}$ $45^{\circ}$ $60^{\circ}$ $90^{\circ}$ Reveal answer Fill a bubble to check yourself D Correct answer Explanation A tangent to a circle is perpendicular to the radius at the point of contact. Therefore, the angle OAB is 90 degrees.