Correct. One way to set up a correct equation is to use the definition of sine.

$\displaystyle{{\sin{{35}}}}^{\circ}=\frac{{o}}{{h}}\usepackage{cmbright}\Huge\$

Use a calculator for the value on the left and the triangle for the ratio on the right:

$\displaystyle{0.5736}\approx\frac{{r}}{{4}}\usepackage{cmbright}\Huge\$

Solve for r: $\displaystyle{r}\approx{4}{\left({0.5736}\right)}={2.2944}\approx{2.29}\usepackage{cmbright}\Huge\$