 #1
stuartgriffin
 3
 0
 Homework Statement:
 A galaxy cluster of mass 3.0 × 1013M⊙ with known distance of 20 Mpc is observed in the centre of a bright ring, which is presumably a lensed galaxy. The angular radius of the ring from the cluster is 1.13 arcmin. The ring is observed to have a redshift of 0.0075. Assuming a value of 70kms−1Mpc−1 for the Hubble constant, determine whether the ring’s redshift distance is consistent at an accuracy of ~5% to the distance expected for the lensed galaxy to actually be located directly behind the cluster.
 Relevant Equations:

a=4GM/bc^2
V=H0D
I have attempted to link the equations, but I don't really understand how the data given fits. Does the angular radius get plugged in as the deflection angle?