var app = angular.module('plunker', ['ui.bootstrap']);

app.controller('MainCtrl', function($scope) {
  var ctrl = this;
  
  ctrl.active = 0;
});
<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <link data-require="bootstrap-css@3.*" data-semver="3.3.6" rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.css" />
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.5.x" src="https://code.angularjs.org/1.5.8/angular.js" data-semver="1.5.8"></script>
    <script data-require="angular-animate@1.5.*" data-semver="1.5.8" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.8/angular-animate.js"></script>
    <script data-require="angular-touch@1.5.*" data-semver="1.5.8" src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.8/angular-touch.js"></script>
    <script data-require="ui-bootstrap@*" data-semver="2.1.3" src="https://cdn.rawgit.com/angular-ui/bootstrap/gh-pages/ui-bootstrap-tpls-2.1.3.js"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MainCtrl as ctrl">
    <button type="button" class="btn btn-default btn-sm" ng-click="ctrl.active = 0">Select first tab - exterior button</button>

    <div class="tabs-container">
      <uib-tabset active="ctrl.active" index="$index">
        <uib-tab heading="tab one">
          tab one
        </uib-tab>
        <uib-tab heading="tab two">
          tab two
          <button type="button" class="btn btn-default btn-sm" ng-click="ctrl.active = 0">
            Select first tab - internal button
          </button>
        </uib-tab>
        <uib-tab heading="tab three">
          tab three
        </uib-tab>
      </uib-tabset>
    </div>
  </body>

</html>
/* Put your css in here */