Answer:
Step-by-step explanation:
[tex]cos~L=\frac{m^2+n^2-l^2}{2mn} \\=\frac{5^2+8^2-7^2}{2*5*8} \\=\frac{25+64-49}{80} \\=\frac{40}{80} \\=\frac{1}{2} \\=cos 60\\[/tex]
∠L=60°
