Mathematics 9709 · AS & A Level · Coordinate geometry

Coordinate geometry — practice question

The diagram depicts a circle with centre $A$ that passes through $B$. A second circle is centred at $B$ and passes through $A$. The tangent at $B$ to the first circle cuts the second circle at $C$ and $D$. The coordinates of $A$ are $(-1, 4)$ and the coordinates of $B$ are $(3, 2)$.
(a)[2]

Find the equation for the tangent $CBD$.

(b)[3]

Find an equation for the circle centred at $B$.

(c)[3]

By calculation, find the $x$-coordinates of $C$ and $D$.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Gradient of $AB$: $m_{AB}=\dfrac{4-2}{-1-3}=-\tfrac12$

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