imagine a semi circle (x-2)+y^2=2 so centre (2,0) and radius 2 for the upper half plane,

call the semi circle p.

I need to give the formula for the reflection across p (hyperbolic reflection) $\displaystyle R_p $

i then have points S=4+3i for example where i need to find $\displaystyle R_p(S) $ i can make stabby attempts but half the other questions depend on getting the correct formula for $\displaystyle R_p $.

thanks,,v desperate.