Q3.(a) what is parallax and how can we use it to determine the distance to a star? why does it take so long for such a measurement to be made? q4.(b) suppose that you want to determine the temperature, diameter, and luminosity of a star. which of these quantities require you to know the distance to the star? explain your reasonings q5.what do we mean by a star's spectral type? by a star's luminosity class? discuss what they tell us about the star and explain how we classify stars by type and class.