The parallax of a star is 0.022 arc seconds

PHYSICS · Subjective · A Level · Physics · Astrophysics · Astrophysics

Problem

The parallax of a star is 0.022 arc seconds. The apparent brightness of the star is

5.0 \times 10^{-10}

W m^-2 and its surface temperature is 4500 K. What is the radius of this star?