Happy Valentine's Day

Ever wanted to know how to draw a heart shaped graph?
There are a number of mathematical equations that can produce heart shapes.


For example you can use this equation-  
And you will see graph like the image below-

I used Grapher on Mac. You can use many other apps like Mathematica, Graph
Try these equations below for more heart shaped graph

1.  

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5. 

Happy Valentine's Day to all