Chapter 13, Trigonometric Ratios and Functions - 13.4 Evaluate Inverse Trigonometric Functions - 13.4 Exercises - Skill Practice - Page 878: 16

$ -0.64$ radians and $-36.87^{\circ}$

In order to get the answer in radians, we need to put the calculator in radians mode. Then, our result will be: $ -0.64$ radians In order to get the answer in degrees, we need to put the calculator in degrees mode. Then, our result will be: $-36.87^{\circ}$