# Question #946b8

##### 2 Answers

#### Explanation:

Transform the given equation into polynomial form using the fact that

Write this quadratic equation in standard form by dividing by 2

Solve the quadratic equation by completing the square. Add 1/2 to both sides

Take half the coefficient of

Factor the left-hand side.

An alternative and a few details.

#### Explanation:

One might also use the Quadratic Formula.

After the step

Therefore

Now observe that

Therefore

However

When we write

Thus

In the third quadrant, the angle with the same reference angle as

The solutions to the equation are

and

Since cosine is an even function, [