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Vexxon

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## Homework Statement

While a planet P rotates in a circle about its sun, a moon M rotates in a circle about the planet, and both motions are in a plane. Let's call the distance between M and P one { lunar unit}. Suppose the distance of P from the sun is 2100 lunar units; the planet makes one revolution about the sun every 2 years, and the moon makes one rotation about the planet every 0.25 years. Choosing coordinates centered at the sun, so that, at time t=0 the planet is at (2100, 0), and the moon is at (2100, 1), then the location of the moon at time t, where t is measured in years, is (x(t), y(t)).

Find equations for x(t) and y(t)

## Homework Equations

Parametric equations of a circle:

x = rcos(t)

y = rsin(t)

## The Attempt at a Solution

My professor says counter-clockwise. I'm adjusting the equations to make it that way.

Using some intuition, I got the equations:

x(t) = 2100*cos(-pi*t) + sin(-2*pi*t)

y(t) = 2100*sin(-pi*t) + cos(-2*pi*t)

in other words, x(t) = x-position of the planet + x-position of the moon. Same for y(t)

I'm fairly sure these equations describe the motion of the moon correctly, but apparently, they are not the correct answers (it's an online submission process).

Any thoughts?

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