| Exam Board | SPS |
|---|---|
| Module | SPS SM (SPS SM) |
| Year | 2021 |
| Session | January |
| Marks | 6 |
| Topic | Circles |
| Type | Find centre and radius from equation |
| Difficulty | Easy -1.2 This is a straightforward question requiring students to complete the square or match coefficients to find the centre from the general circle equation, then use the standard form to find the radius. It involves routine algebraic manipulation with no problem-solving insight needed—easier than average A-level questions. |
| Spec | 1.03d Circles: equation (x-a)^2+(y-b)^2=r^21.03e Complete the square: find centre and radius of circle |
7.
A circle whose centre is at $( 3 , - 5 )$ has equation
$$x ^ { 2 } + y ^ { 2 } - 6 x + a y = 15$$
where $a$ is a constant.\\
a) Find the value of $a$.\\
b) Determine the radius of the circle.\\
\hfill \mbox{\textit{SPS SPS SM 2021 Q7 [6]}}