Y is inversibly prportional to x when y=7 x=9 work out the value when x=21
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Answer:
The distance between the hands is √(3)cm ≈ 1.73cm.
Step-by-step explanation:
In a standard clock, the angle between every number is 30°, therefore the angle between 12 and 2 will be 30° x 2 = 60°.
Looking at the diagram, to find c we can make use of our cosine formula
c² = a² + b² –2abCos(C°)
a = 2, b = 1 and C° = 60°
Therefore we have:
c² = 2² + 1² –2 x 2 x 1 x cos(60°) =
c² = 4 + 1 – 4 x 0.5 =
c² = 5 – 2 =
c² = 3
c = √(3) ≈ 1.73
Therefore, the distance between the hands is √(3)cm ≈ 1.73cm.
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.