Calculate the effective gravitational field vector g at Earths surface at the poles and the equator. Take

Question:

Calculate the effective gravitational field vector g at Earth’s surface at the poles and the equator. Take account of the difference in the equatorial (6378km) and polar (6357km) radius as well as the centrifugal force. How well does the result agree with difference calculated with the result g = 9.780356[1 + 0.0052885 sin2λ -0.0000059 sin2 (2λ) m/s2 where λ is the latitude?