We'll begin by transforming the 48' (arc minutes) into a decimal numer. Since they are arc minutes, we can think of them as 48/60 minutes, this is:
[tex]\frac{48}{60}=0.8[/tex]
In other words, 48 arc minutes equal 0.8 degrees. From here we can use a calculator to get the following result:
Round to the nearest hundredth:
[tex]\cos (256.8)=-0.23[/tex]
