Question: how to calculate the correlation coefficient on desmos?
Answer: To have Desmos calculate your R2 value in a new input line type y1 ~ a(x1-h)^2+k. Desmos uses y1 to represent the y-value in a data table and x1 to represent the x-values in a table. Adjust your sliders until you get the highest possible value for R². Write down your equation of best fit.