Check and Uncheck radio buttons using AngularJS

Code:
<!DOCTYPE html>
<html ng-app="" ng-controller="myCtrl">
<body>
<h4>Click on below buttons to check and uncheck radio buttons</h4>
<button ng-click="gender = 'male'">Select Male</button>
<button ng-click="gender = 'female'" >Select Female</button><br>
<input type="radio" ng-model="gender" value="male" name="gender"/> Male<br>
<input type="radio" ng-model="gender" value="female" name="gender"/> Female<br>
<h4>Gender Value</h4>
<div ng-bind="gender"></div>
<script>
function myCtrl($scope) {
    $scope.gender = 'male';
}
</script>
<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.2.15/angular.min.js"></script>
</body>
</html>