Question
cosA= 5/9 find cos1/2A
are you familiar with the half-angle formulas?
the one I would use here is
cos A = 2cos^2 (1/2)A - 1
5/9 + 1 =2cos^2 (1/2)A
14/9 =2cos^2 (1/2)A
cos (1/2)A = √(7)/3
are you familiar with the half-angle formulas?
the one I would use here is
cos A = 2cos^2 (1/2)A - 1
5/9 + 1 =2cos^2 (1/2)A
14/9 =2cos^2 (1/2)A
cos (1/2)A = √(7)/3