PLEASE HELP <3 What is the radius of the event
horizon for Cygnus X-1?
A. 21 m
B. 21 km
C. 21 AU
D. 21 light years

(Assume that Cygnus X-1 has 7 times the mass of the Sun and is not rotating. One solar mass = 1.99 x 10^30 kg)

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

vapour or gas assuming atmospheriv pressure

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.