### Home > A2C > Chapter 13 > Lesson 13.1.3 > Problem13-56

13-56.

For each of the following problems, find all of the solutions without using a calculator. Use a graph or unit circle to support you answers. Then predict the solution that your calculator will give and use your calculator to check your prediction.

1. $4 \operatorname { sin } ( x ) + 2 = 0$

$\text{sin}(x)=-\frac{1}{2}$

$x=\frac{7\pi}{6}+2\pi n,\,\,x=\frac{11\pi}{6}+2\pi n$

1. $2 \operatorname { cos } ( x ) = \sqrt { 3 }$

See part (a).

1. $\operatorname { tan } ( x ) + 1 = 0$

See part (a).

1. $4 \operatorname { cos } ^ { 2 } ( x ) - 4 = 0$

$\operatorname{cos}^{2}\left(x\right) = 1$

$x = πn$