Formamide has the structure $\mathrm{HC}\left(\mathrm{O}\right){\mathrm{NH}}_2$ Which atoms in formamide have a trigonal planar geometry?

Formamide has the following Lewis structure. The SN of the C atom is 3. The trigonal planar geometry and $s{p}^2$ hybridization are consistent with this. As a result, the C and all of the atoms (N) that are directly linked to it are in the same plane and at $120°$ angles.