# Daily Desmos 218a (Advanced)

## Creator

Justin Lanier (@j_lanier)

## Difficulty

Advanced

## On to the Challenge!

Can you create the following graph using desmos.com or some other graphing tool? **Notice that this advanced challenge is the envelope curve of the family of lines in the basic challenge (218b)**. If you’re victorious, leave us a note in the comments when you’re done.

Not sure what the equation of the curve is…. working on it. Here are the lines:

https://www.desmos.com/calculator/sblnfvsyaj

Bam. https://www.desmos.com/calculator/sfv8g3qlwm

Whoops, erroneously titled that graph “218b” instead of “218a.”

Gah, I retract my earlier “solution.” It’s not quite right.

Okay, NOW I think I have it. https://www.desmos.com/calculator/rdqublvxwt

Provided implicitly defined curves are ok, here’s mine:

https://www.desmos.com/calculator/s71fd1qziw

I went down the rabbit hole on this, creating a parametrically defined curve, converting that to a function of y, and then making it implicit to get rid of a +/- in there. Yikes.