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Pleas help! exam tommarow Trigonometry word problems

  1. Jun 14, 2006 #1


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    Pleas help! exam tommarow!!!! Trigonometry word problems

    Hi, i really need help with this question,

    on a wall, a spider is 100cm above a fly. the fly starts moving horizontally at the speed of 10cm/s. After 1s, the spider begins moving at twice the speed of the fly, in such a way as to intercept the fly by taking a straight line path. In what direction does the spider move, and how far has the fly moved when they meet?

    How do I do this question? it just sayes the fly moved horizonally how do you know witch way it went, wont that determine where the spider went??? and I oll have one measure ment 100cm??? Can someone pleas help me throught the problem? I really don't know where to start
  2. jcsd
  3. Jun 15, 2006 #2


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    The fly is moving horizontally at 10 cm/s. In "t" seconds, it will have moved 10t cm from directly below the spider. If the spider at 20 cm/s, 1 second after the fly, t seconds after the fly started moving), it will have moved 20(t- 1) cm. (do you see why it is "t-1"?) If you draw the three lines connecting the spider's original position, the fly's original postion, and the point where they meet, you will have a right triangle with legs of length 100 cm and 10t cm, and hypotenuse of length 20(t-1) cm. Use the Pythagorean theorem to determine t and then use trig functions to determine the angles in the triangle.
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