Question

Find all solution of the following equation in the interval [0, 2pi) No decimals.

Answer 1

Step-by-step explanation:

Step 1:  Add 2cos(x) to both sides

$7cos(x) + 2cos(x) + 9 = -cos(x) + cos(x)$

$9cos(x) + 9 = 0$

Step 2:  Subtract 9 from both sides

$9cos(x) + 9 - 9 = 0 - 9$

$9cos(x) = -9$

Step 3:  Divide both sides by 9

$9cos(x) / 9 = -9 / 9$

$cos(x) = -1$

Step 4:  Find x

$cos^-^1(-1) = x$

$\pi = x$

Answer:  $x = \pi$