How do i hide/show a SVG element with a button while using angularJS for giving some input?

I am writing this code but it doesn't run properly.

<div class="app" ng-app>
<div ng-controller="ctrlSizing">
    <label id="rad" style="visibility: hidden">Radius: <input ng-model="rad" type="number" placeholder="How about 300?"></label>
    <div style="height: 800; width: 500; position:absolute; left: 100px;top: 100px;">
        <svg width="500" height="500" visibility="hidden" onclick="cInput()" >
            <circle id="circle1" cx="150" cy="150" ng-attr-r="{{rad}}" stroke="black" stroke-width="2" fill="grey" />
        </svg>
    </div>
</div>