Question

Cos(0.5)+cos(0.5+2(3.14159265))+cos(0.5+4(3.14159265))

Answer 1

2.63274768567

Explanation:

First, note that 3.1415... is p, so 2(3.1415...) is 2pi and 4(3.1415...) is 4pi.

2pi and 4pi are full rotations, which will lead to the same cosine (i.e. cos(x) = cos (x+2pi) = cos(x+4pi) = ... = cos (x+2k*pi)).

So, the expression equals cos0.5 + cos 0.5 + cos0.5 = 3cos0.5 = 3(0.87758256189) = 2.63274768567

I hope this helps! :)