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Related Rates triangle

  1. Mar 15, 2004 #1
    Hello here's the problem:

    Each of the two sides of a triangle are increasing at the rate of 1/2 foot per second, and the included angle is decreasing 2 degrees per second. Find the rate of change of the area when the sides and included angle are respectively 5ft., 8ft., and 60 deg.

    Here is my question: How do I find the height of the triangle?
    Say my base is 5ft. How do I express it in terms of the given details in the problem?
  2. jcsd
  3. Mar 15, 2004 #2

    matt grime

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    Try finding a better formula for the area of a triangle involving the two given sides and the included angle. (Think vector cross products, perhaps.)
  4. Mar 15, 2004 #3


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    Area= (1/2) height times base where the "height" is measured perpendicular to the "base". Take one of the given sides as base, and drop a perpendicular to it. The other given side is the hypotenuse of the right triangle formed. The height you need is the "opposite side" of that right triangle.
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