Challenging Questions

Mathematics – Compulsory Part

Learning Unit: Equations of circles

Question M0-13-01

Consider two circles,

\(C_1: x^2 + y^2 – 6x – 8y = 0\)

\(C_2: x^2 + y^2 – 18x + 8y + 72 = 0\)

1. By converting \(C_1\) into centre-radius form, find the centre and radius of \(C_1\).
2. By using the general formula, find the centre and radius of \(C_2\).
3. Hence, show that \(C_1\) and \(C_2\) touch each other externally.

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