Solve Determine all values of x in the interval 02pi Give ex

Solve. Determine all value(s) of x in the interval [0,2pi). Give exact value(s) where possible.

cosx= -0.6031

Solution

cosx = -0.6031

x = cos^-1(-0.6031)

(cos is -ve in IInd and IIIrd quadrant)

x = pi - 0.923 ; x= pi+ 0.923

In the interval [ 0, 2pi) x = 2.218 rad ; x = 4.06 rad