How do you solve 2sinx + 1 =0?

1 Answer
Acquaintance · Stefan V.
May 27, 2016

x = (11pi)/6, (7pi)/6

Explanation:

To solve this equation, go about it as you would any other equation. Get the sin x all by itself.

2 sin x +1 = 0

2 sin x = -1

sin x = -1/2

Then, use the unit circle to find all radian values which have a y-coordinate of -1/2, since sin is the y value (as opposed to cos, which is the x value).

![www.math.toronto.edu)

As you can see, the coordinates (-sqrt(3)/2, -1/2) and (sqrt(3)/2, -1/2) have y values (or sin values) of -1/2.

The radian correspondents of these coordinates are (7pi)/6 and (11pi)/6, and those are your two answers.

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