Evaluating cos (2arctan radical 6 + Pai / 3)

Evaluating cos (2arctan radical 6 + Pai / 3)

Cos (2arctan radical 6 + π / 3) = cos (2arctan radical 6) cos (π / 3) - sin (2arctan radical 6) sin (π / 3) = {2cos ^ 2 (arctan radical 6) - 1} * 1 / 2-2sin (arctan radical 6) cos (arctan radical 6) * 1 / 2 * radical 3 = cos ^ 2 (arctan radical 6) - 1 / 2-sin (arctan radical 6) cos (AR