Yes, i have a site online which uses that method serhat, works well:
sqrt(power(69.1*(lat - “.$baselat.”),2)+power(69.1*(lng - “.$baselng.”)*cos(lat/57.3),2))
where $baselat and $baselng are centre and lat,lng are table fields
(returns miles, not Km as I am in UK)
Implemented before custom queries I may add so it is part of a custom piece of code, not tried it with the new Wappler custom query