## Geometry: Common Core (15th Edition)

According to the side-splitter theorem, if a line is parallel to a side of a triangle and intersects the other two sides, then those two sides are divided proportionately. This means that the two triangles pictured are similar to one another. $x = 10$
According to the side-splitter theorem, if a line is parallel to a side of a triangle and intersects the other two sides, then those two sides are divided proportionately. This means that the two triangles pictured are similar to one another. Let's set up a proportion for the sides whose values are given in the figure: $\frac{x}{14} = \frac{20}{28}$ Use the cross products property to get rid of the fractions: $28x = 280$ Divide each side of the equation by $28$ to solve for $x$: $x = 10$