Is this equation a function?

y = -3x^2 + 10

Yes, it is a function as for every x value there is only one y value, you could also see that it is not a function by doing the vertical line test, this equation passes it.

dont't really have enough info here but its likely

sss for the three sides being congruent ( its stands for side side side)

or

sas   for side angle side.   so a side is congruent and and angle and a side