Question

Find all solutions in radians. Approximate your answers to the nearest hundredth. (Let k be any integer.)

Answer 1

Answer: 0.73 + πk, 0.28 + πk

Explanation:

      cos (2x - 1) = 0.9

cos⁻¹[cos (2x - 1)] = cos⁻¹ 0.9

               2x - 1 = +/- 0.45

               2x      = +/- 0.45 + 1

                  x      = $\frac{+/- 0.45 + 1}{2}$

                  x      = $\frac{0.45 + 1}{2}$,   x  = $\frac{-0.45 + 1}{2}$

                  x      = 0.73, 0.28

For ALL Solutions:

x = 0.73 + πk         and        x = 0.28 + πk