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Math Help - Related Rates question 2

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    Exclamation Related Rates question 2

    Two cyclists depart at the same time from a starting point along routes making an angle of 60 degrees with each other. The first is travelling at 15km/h, while the second is moving at 20km/h. How fast are the two cyclists moving apart after 2 hours?
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    Quote Originally Posted by math123456 View Post
    Two cyclists depart at the same time from a starting point along routes making an angle of 60 degrees with each other. The first is travelling at 15km/h, while the second is moving at 20km/h. How fast are the two cyclists moving apart after 2 hours?
    You know the lengths of the two sides of a triangle and the angle between the two sides so you can use the cosine law, c^2= a^2+ b^2- 2ab cos(C) to get a formula for the third side, the distance between them. Differentiate to get a formula connecting the rates.
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