| Exam Board | Edexcel |
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| Module | F3 (Further Pure Mathematics 3) |
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| Year | 2014 |
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| Session | June |
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| Topic | Conic sections |
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2. The line with equation \(x = 9\) is a directrix of an ellipse with equation
$$\frac { x ^ { 2 } } { a ^ { 2 } } + \frac { y ^ { 2 } } { 8 } = 1$$
where \(a\) is a positive constant.
Find the two possible exact values of the constant \(a\).