What is the exact value for cos(-2\pi/3)? This should be done without a calculator. Please explain the process if possible.

Question

What is the exact value for cos(-2
`\pi`/3)?

This should be done without a calculator.
Please explain the process if possible.

Answer 1

notice the picture below

see where that angle is?

check your Unit Circle for that value

also notice, that fractions of
`\pi` are just like grabbing 180 degrees and splitting it, so one third of 180 or
`\pi` is 180/3 or 60 degrees