Part A Estimate the diameter of the supergiant star Betelgeuse, using its angula

Question

Part A

Estimate the diameter of the supergiant star Betelgeuse, using its angular diameter of about 0.05 arcsecond and distance of about 600 light-years. Express your answer to three significant figures and include the appropriate units.   
DBetelgeuse =   
  
Part B

Compare your answer to the size of our Sun. The diameter of the Sun is 1.39 million km. Express your answer using three significant figures.   
DBetelgeuse / DSun =   

Part C

Compare your answer to the average Earth-Sun distance. Express your answer using two significant figures.    DBetelgeused / Sun?Earth =

Explanation / Answer

1) angle (in rad) = d/D where d = diameter and D = distance. Those both have to be in the same units, so either convert 600 light years to km before solving, or convert d to km after solving.

0.05 arcsec (in rad) = d in light years/600 light years

or

0.05 arcsec (in rad) = d in km/600 light years in km

one light year - 9.4605284x10^12kms

2.42e-7*5676*e12 = d

d= 13735.92e5

2) 13735.92e5/(1.39*10^6) = 988.19

c)

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