b cos 2x Solutioncos2x 1sqrt2 2x cos11sqrt2 General soluti

Solution

cos2x = 1/sqrt2

2x = cos^-1(1/sqrt2)

General solution :

2x = pi/4 +2k*pi

x = pi/8 +k*pi = (pi +8kpi)/8

x =  (pi +8kpi)/8 -----(1)

2x = 2pi -pi/4 +2k*pi

= 7pi/4 +2k*pi

x = (7pi +8kpi)/4 ------(2)

Since interval for which angles have to be found is not given we would find

agles in the interval in the interval [ 0, 2pi)\\

Plug k =0,1 in equation 1 and 2 :

x = pi/8 , 7pi/8 , 15pi/8 , 9pi/8 (Solution)