First, let's graph the trapezoid.
The midsegment refers to a segment that goes from the midpoint of BC and the midpoint of AD.
Let's find the midpoints using the following formula


Now, we use the distance formula to find the length of the midsegment
![\begin{gathered} d=\sqrt[]{(y_2-y_1)^2+(x_2-x_1)^2} \\ d=\sqrt[]{(-1-5)^2+(10-1)^2}=\sqrt[]{(-6)^2+(9)^2} \\ d=\sqrt[]{36+81}=\sqrt[]{117} \\ d\approx10.8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/wjv0s08cacfzh8awaidcpwnnw5pzxdc805.png)
Hence, the length of the midsegment is 10.8, approximately.