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Solve on the interval [0,2π):

1+sin8 = 1/2

A. 7π/6, 11π/6
B. π/6, 5π/6
C. 2π/3, 4π/3
D. π/3, 5π/3

User Miledys
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1 Answer

6 votes

We are given the equation 1+sin8 = 1/2 and we need to find its solution on the interval [0,2π).

To solve this equation, we will start by isolating the sine term.

1 + sin8 = 1/2

Subtracting 1 from both sides, we get:

sin8 = -1/2

Now, we need to find the angles on the interval [0,2π) that have a sine of -1/2.

The sine function is negative in the third and fourth quadrants of the unit circle. Therefore, we will look for angles in these quadrants that have a sine of 1/2.

To find these angles, we will use the fact that the sine function is equal to the y-coordinate of the point on the unit circle.

Let's start with the third quadrant. In this quadrant, the x-coordinate is negative and the y-coordinate is negative. Therefore, we can write:

sinθ = -1/2 = sin(π - θ)

This gives us:

π - θ = arcsin(-1/2) = -π/6

θ = π + π/6 = 7π/6

Now, let's move on to the fourth quadrant. In this quadrant, both the x-coordinate and the y-coordinate are positive. Therefore, we can write:

sinθ = -1/2 = sin(2π - θ)

This gives us:

2π - θ = arcsin(-1/2) = -π/6

θ = 2π + π/6 = 11π/6

Therefore, the solutions of the given equation on the interval [0,2π) are:

A. 7π/6, 11π/6

And the correct option is A.

User Mohamed Murashid
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7.6k points