Calculating Angle and Frequency of Mars-Sun Opposition

[dswatson]

Mars orbits the sun at a mean orbital radius of 228e9 m and has an orbital period of 687 d. Earth orbits the sun at a mean orbital radius of 149.6e9 m.
a)The earth-sun line sweeps out an angle of 360 degrees during one earth-year. Approximately what angle is swept out by the Mars-sun line during one Earth-year?
b) How frequently are Mars and the sun in opposition (on diametrically opposite sides of Earth)?


I do not know any relavant equations or even how to begin this problem we were given this homework as we walked out of the room without covering all of the necessary material.
Any help would be greatly appretiated. Thank you.

 

[mgb_phys]

A, is simply asking what proportion of a Mars year is one Earth year.

 

[dswatson]

A, is simply asking what proportion of a Mars year is one Earth year.

so is it as simple as...

365.24d/360=687/x

then solve for x?

 

[mgb_phys]

Almost, 365.24/687 = x/360
A Mars year is about twice an Earth year, so you should get an answer of about half a full circle

 

[dswatson]

just wanted to say thanks