## Algebra 1: Common Core (15th Edition)

To determine the slope of second bird that flew to perpendicular to first bird, find the slope of the first bird. The perpendicular slope would be the negative reciprocal of the original slope. First Bird (1,2), (5,4) Slope = $\frac{Rise}{Run}$ = $\frac{Y2-Y1}{X2-X1}$ = $\frac{4-2}{5-1}$ = $\frac{2}{4}$ = $\frac{1}{2}$ Slope of First bird = $\frac{1}{2}$ Slope of Second bird = -$(\frac{1}{2})^{-1}$ = -2