Given:
In triangle UVW, X is the midpoint of UV and Y is the midpoint of VW.
[tex]m\angle XYV=7x+21[/tex]
[tex]m\angle UWY=91-7x[/tex]
To find:
The measure of angle XYV.
Solution:
Since X is the midpoint of UV and Y is the midpoint of VW, therefore XY is the mid-segment of the triangle UVW and parallel to the base of the triangle, i.e., UW.
If a transversal line intersect two parallel lines, then the corresponding angles are congruent and their measures are equal.
[tex]\angle XYV \cong \angle UWY[/tex] [Corresponding angle]
[tex]m\angle XYV=m\angle UWY[/tex]
[tex]7x+21=91-7x[/tex]
We need to solve this equation for x.
[tex]7x+7x=91-21[/tex]
[tex]14x=70[/tex]
[tex]x=\dfrac{70}{14}[/tex]
[tex]x=5[/tex]
Now,
[tex]m\angle XYV=7x+21[/tex]
[tex]m\angle XYV=7(5)+21[/tex]
[tex]m\angle XYV=35+21[/tex]
[tex]m\angle XYV=56[/tex]
Therefore, the measure of angle XYV is 56 degrees.