if I have the velocity of the planetary orbit and the mass of the sun, how do I get the radius of the orbit?

You know jwveverka you probably not have to learn maths all over. The maths on Earth is the same as the maths in outer space.

Maybe maths is different in Brazil though

http://web2.0calc.com/questions/i-come-from-brazil-and-for-me-2-2-should-be-2-times-2-4-in-us-this-is-4-i-am-telecommunication-engineer-and-know-about-math-is-this

v = √(G*M/r) can be rewritten as v² = G*M/r, which can then be rearranged as r = G*M/v²

 

$${\mathtt{r}} = {\frac{{\mathtt{6.67}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{\left(-{\mathtt{11}}\right)}{\mathtt{\,\times\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{\left({\mathtt{30}}\right)}}{{\left({\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{4}}}\right)}^{{\mathtt{2}}}}} \Rightarrow {\mathtt{r}} = {\mathtt{333\,500\,000\,000}}$$

 

r = 3.335*10¹¹ m

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