Edexcel IGCSE Maths Problem-Solving and Reasoning

Two circles, $C_{1}$ and $C_{2}$, are drawn on a centimetre grid, with a scale of 1 cm for 1 unit on each axis.

The centre of circle $C_{1}$ is at the point with coordinates (-1,3) and the radius of $C_{1}$ is 13 cm.

The centre of circle $C_{2}$ is at the point with coordinates (7,18) and the radius of $C_{2}$ is 6 cm.

Explain why circle $C_{1}$ intersects circle $C_{2}$