I have a friend that had an i9 Mac that fried itself. It wa$ a traumatizing experience. I don’t remember the details but he couldn’t get it fixed / replaced in Brazil, I guess due to being bought is the US… something like that.
The Ymas Tree should be upside down, Shirley?
How could Santa put presents under it then? 
If the base of Xmas tree is at 0 and the top is at some positive number > 0, wouldn’t the Ymas tree’s base be at zero and the top at some positive number > 0? Plus, as Brian said, you couldn’t put presents under it if it were upside down.
This is a computing forum and not a mathematical one. Y increases in the downwards direction. This also means that Sant’s sleigh has to fly upside down.
The graphic is right. X increases to the right, Y increases to the top and Z increases as shown from the plane to you.
You are not a matematician 
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Santa always flies upside down in Australia!
Wish all a Merry Christmas and Happy Hanukkah. This time of year has celebrated religious holidays for over 2,000 years. Maybe we should continue to acknowledge them.
Not if the world is flat.
I thought Santa sat on the right side of the sled to drive in Australia?
Yes / and the sleigh is pulled by 6 white “Boomers”(Giant Kangaroos)
