$$4.543=R\left(1-\frac{cos(28.65*200.53)}{R}\right)\\\\
4.543= R\left(1-\frac{cos(5745.1845)}{R}\right)\\\\
4.543\approx R\left(1-\frac{-0.7049}{R}\right)\\\\
4.543\approx R\left(1+\frac{0.7049}{R}\right)\\\\$$
Now multiply both sides by R, take it all to one side and put =0, solve it as a quadratic equation.
I have not done this so I don't know what the answer will be.
You do it - if you have problems then post again.