physics
posted by anon turtle .
Calculate the mass of the star using the fact
that the period of the planet is 3.07 × 107
s
and its distance from the star is 1.26×1011 m.
Answer in units of kg

The orbital period is given by
T = 2π√(r^3/GM)
We want M, which is thus
M = r^3/G * (2π/T)^2
Now just plug in your numbers.