CCSS IP Math III 3.2.2 Example 2

Given the diagram of [math]\triangle DEF[/math], find the length of side [math]f[/math]. Round the length to the nearest tenth.

[list=1] [*]Identify which values are equivalent to [math]a[/math], [math]b[/math], and [math]c[/math] in the Law of Cosines formula. [*]Substitute the known values into the Law of Cosines formula. [*]Solve the resulting equation for [math]f[/math]. [/list]