Answer:
The required co-ordinate is (-2, -5).
Step-by-step explanation:
For a given point, reflection of a point (x, y) across a horizontal line y = k, the reflected co-ordinates will be: .
Here, (x, y) = (-2, 7) then reflection along the line y = 1, we get:
= (-2, -5)
The reflected point is (-2, -5).
Since the beacons rotate together, the angular speed is constant.
From the time you see the first beacon, you have to wait for the lighthouse to make 120°, i.e. 1/3 of a whole turn.
So, if T is the time it takes for the lighthouse to make a whole turn, the interval between the first and the second beacon is T/3.
The interval between the second and third beacon is the amount of time it takes to the lighthouse to make the remaining 2/3 of a turn, so that you'll see the first beacon again. So, this time is 2T/3
So, the ratio is
So, the time between the second and third beacon is twice as much the time between the first two.