Illustrated Glossary of Organic Chemistry

Tetrahedral carbon: A carbon atom with four attachments, and bond angles of approximately 109.5o. The overall shape is that of a tetrahedron (i.e., a pyramid with all faces being equilateral triangles, or nearly so). The carbon atoms uses sp3 orbitals to achieve this geometry. When all four attachments are different, the carbon is a stereocenter.

All H-C-H bond angles are 109.5o.
The carbon is not a stereocenter.
Molecular model of methane.
Build one for yourself to verify
the tetrahedral geometry.

(R)-Bromochlorofluoromethane. All bond angles approximately 109.5o.
The carbon has four different attachments, and thus is a stereocenter.