COUNTDOWN 26 A circle whose center is at (3, -5) has equation $x^2 + y^2 - 6x + ay = 15$, where $a$ is a constant. a) Find the value of $a$. [4 marks] b) Determine the radius of the circle. [3 marks]
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In this case, the center of the circle is (3,-5), so the equation of the circle is (x-3)^2 + (y+5)^2 = r^2. Show more…
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