[tex]\qquad[/tex] [tex]\purple{\twoheadrightarrow\pmb{AC= \sqrt{AB^{2} + BC^{2} -2AB\times BC\cos(\alpha)}}}[/tex]
Substituting the data, we get the following:
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf {AC= \sqrt{(4)^{2} + (6)^{2} -2(4)(6)\cos(60^{\circ})}}[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf {AC= \sqrt{16+ 36 -48(1/2)}}[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf {AC= \sqrt{52-24}}[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf {AC= \sqrt{28}}[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf {AC= 2\sqrt{7}}[/tex]
[tex]\qquad[/tex] [tex]\purple{\twoheadrightarrow\pmb{AC= 5.30\ cm}}[/tex]