I have two trend lines generated from the same data. As you can in the chart, the polynomial trend line creates an R squared value of 1. The linear regression trendline creates an R squared value of 0.148.

My data set is

X | Y |

57.5 | 16.56 |

52 | 16.34 |

54 | 16.76 |

Using LINEST(B2:B4,A2:A4^{1,2}), I can get the co-efficients of the polynomial.

Using LINEST(B2:B4,A2:A4), I can get the slope and intercept of the linear trend line.

Using RSQ(B2:B4,A2:A4), I can get the R-Squared value of the linear trend line

How can I get the R-Squared value of the polynomial from the same dataset?

I have tried a few alternative methods to calculate the R Squared and it always calculates the values for the Linear Trend line, not the polynomial.

I really would like to have both R-Squared values in the same sheet, so the I can switch formulas as the data changes.

Thanks in advance