Step 1:

-coordinate is .

-coordinate is .

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The distance from the point is .

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Step 2:

The rate of change in distance with respect to is .

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Apply derivative on each side with respect to .

The rate of change at .

Find and .

.

.

.

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Step 3:

.

The rate of change in distance at is

Substitute and in above expression.

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The rate of change in distance at is .

Solution:

The rate of change in distance at is .