What are the modulus $\left ( r \right )$ and argument $\left ( \theta \right )$ of the complex number $3+4i$ ?
- $r=\sqrt{7}, \theta =tan^{-1}\left ( \frac{4}{3} \right )$
- $r=\sqrt{7}, \theta =tan^{-1}\left ( \frac{3}{4} \right )$
- $r={5}, \theta =tan^{-1}\left ( \frac{3}{4} \right )$
- $r={5}, \theta =tan^{-1}\left ( \frac{4}{3} \right )$