It's complementary, which is a different word and has a very specific meaning when it comes to colour theory (a colour's complement is the colour directly opposite it on a colour wheel) https://en.wikipedia.org/wiki/Complementary_colors
Convert #ee4035 to rgb(234, 64, 53). Subtract those values from max RGB domain (255) and take square root of difference of squares. i.e sqrt(255^2 - 238^2) etc.
You end up with rgb(92, 247, 250), or the cyan color mentioned above. You can also check this in several other complementary calculators.
I could be missing something.
1: https://en.wikipedia.org/wiki/Complementary_colors#Colors_pr... 2: https://en.wikipedia.org/wiki/Color_wheel