Draw a picture of the problem.
let ∅ be the angle formed in the first quadrant such that its y coordinate is twice its x coordinate.
The lengths are denoted 2a and a.
Joining the point (0, 0) to the point described, in the first quadrant, we have a right triangle with side lengths
, where 
is the hypotenuse, found by the Pythagorean theorem.
sin∅=opposite side/hypotenuse=
Now consider the reflection of the red line segment with respect to the x-axis, the ratio of the distances described still holds. Since here we are in the fourth quadrant, the sine is negative, so sin is
.
Answer: {
}
let ∅ be the angle formed in the first quadrant such that its y coordinate is twice its x coordinate.
The lengths are denoted 2a and a.
Joining the point (0, 0) to the point described, in the first quadrant, we have a right triangle with side lengths
sin∅=opposite side/hypotenuse=
Now consider the reflection of the red line segment with respect to the x-axis, the ratio of the distances described still holds. Since here we are in the fourth quadrant, the sine is negative, so sin is
Answer: {