Identify the property used in each step.

12.2 + 186+-4.3 + (-186)

12.2+-43 + 18.6+(-186)

122+ -43 + [18.6 + (-186)]

12.2 + 4.3 + (0)

122 + 43

7.9

A3cm×3cm\greend{3\,\text{cm} \times 3\,\text{cm}} 3cm×3cm start color greend, 3, space, c, m, times, 3, space, c, m, end color greend rectangle sits inside a circle with radius of 4cm\blued{4\,\text{cm}} 4cm start color blued, 4, space, c, m, end color blued . what is the area of the shaded region? round your final answer to the nearest hundredth.