7. The midpoints of the three sides of a triangle are $\left(\frac{1}{4}, \frac{13}{4}\right) 、\left(-\frac{1}{2}, 1\right) 、\left(-\frac{5}{4}, \frac{5}{4}\right)$, then the coordinates of the three vertices are .
7. $(-2,-1) 、\left(-\frac{1}{2}, \frac{7}{2}\right) 、(1,3)$ Hint: Use the midpoint formula to set up three systems of equations.