I want to create this triangular/polygonal shape using SVGs and assign it a background image.
<svg class="svg-graphic" width="100%" height="100%" class="svg-graphic" viewBox="0 0 100 100" >
<defs>
<pattern id="image" x="0" y="0" patternUnits="userSpaceOnUse" height="1" width="1">
<image x="0" y="0" xlink:href="http://25.media.tumblr.com/fe6e34ef00254f2bd05451f525b02324/tumblr_mw8osqc77F1qdrz3yo3_500.jpg"></image>
</pattern>
<polygon points="0, 0, 100, 0, 50, 50" fill="url('http://25.media.tumblr.com/fe6e34ef00254f2bd05451f525b02324/tumblr_mw8osqc77F1qdrz3yo3_500.jpg')"/>
</defs>
</svg>
Very similar to this question here:
Happy Chanukkah