Question 16Which of the following describes the set of values of $a$ for which the curves $x^2 + y^2 = a^2$ and $y = x^2 - a$ in the real $xy$-plane intersect at exactly $3$ points?$a = \tfrac14$$\tfrac14 \lt a \lt \tfrac12$$a \gt \tfrac14$$a = \tfrac12$$a \gt \tfrac12$