# Quiz

In the diagram, the circumference of the external large circle is
1) longer, or
2) shorter, or
3) equal to,
the sum of the circumferences of all inner circles centered on the common diameter, tangent to each other.

$\displaystyle d = \sum_{j} d_j$
$\displaystyle \pi. d = \pi. \sum_{j} d_j= \sum_{j}\pi.d_j$