Hi,
Answering whether you need ajax.googleapis.com ..../angular.min.js, the way of referencing Angular library is changed from AngularJS version to later versions of Angular.
Use Angular CLI or any seed which will scaffold the project(skeleton project) for you and it will be inherently included and you will see package.json specifiying the version of angular and other relevant libraries versions.
short answer, use any seed project(skeleton project) of Angular
https://github.com/angular/angular-seed (download this code) acts as skeleton project for you
or
https://cli.angular.io/, refer how to install Angular CLI to scaffold angular skeleton project