\input zb-basic \input zb-ioport \iteman{io-port 01761949} \itemau{Fayet, M.} \itemti{Bobillier formula as a fundamental law in planar motion.} \itemso{ZAMM, Z. Angew. Math. Mech. 82, No. 3, 207-210 (2002).} \itemab Summary: The author returns to a new formula which he called Bobillier formula. He found it thanks to an original geometric interpretation of Euler-Savary's formula. Here is a short presentation of it. This Bobillier formula may also be obtained without using the Euler-Savary's formula. The latter then appears as a particular case. That is why Bobillier formula is presented as a fundamental law in planar motion. \itemrv{~} \itemcc{} \itemut{} \itemli{doi:10.1002/1521-4001(200203)82:3<207::AID-ZAMM207>3.0.CO;2-T} \end