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Unformatted text preview: θ θ y x r P(x,y) y coordinate of P x coordinate of P Trigonometry Facts and PSHomework # 1 (PS_HW1) From your early school days, you probably remember vaguely some trigonometric facts. Trig. is a vital element of ALL calculations in many branches of engineering. In order to do it fast and accurately, you need to memorize a few facts. You probably remember that for a right angle as shown: adjacent opposite hypotenuse adjacent hypotenuse opposite = = = θ θ θ tan cos sin The problem with these is that THEY WORK ONLY FOR ACUTE ANGLES θ . For example, for the following triangle, how do you find sin θ , cos θ , and tan θ ? Well, you cannot do it so easily! You have to remember all kinds of formulae regarding quadrants etc. One answer, and one that always works (though it is not always convenient), is to use Cartesian coordinates and measure all angles CCW from the positive xaxis as shown: Once you have marked the x and y coordinates of the tip (point P ), then sin θ , cos θ , and...
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 Spring '10
 Reddy
 Trigonometry, Law Of Cosines, tan θ, following triangle, calculus book

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