Exercise PhysicsWiki

$$a=b$$

$\nabla \cdot {\overrightarrow {B}}=0$ (posted by TerriC, Group 2)

$e^{i\theta }=cos(\theta )+isin(\theta )$ (Zach McDargh)

$f\lambda =c$

$r={\frac {p}{1+\varepsilon \cdot \cos \theta }}$ (posted by KimberlyWynne 19:05, 29 August 2009 (EDT))

$x={\frac {-b\pm {\sqrt {b^{2}-4ac}}}{2a}}$ (Sandy Simmons)