Finding AnglesDate: 9/6/96 at 19:57:14 From: BARRY CALDWELL Subject: Finding Angles of a Right Triangle How do you compute the other two angles of a right triangle? I know the hypotenuse and the other two lengths, but how do I get the other two angles? Sincerely, Barry Caldwell Date: 9/6/96 at 20:16:0 From: Doctor Tom Subject: Re: Finding Angles of a Right Triangle Hi Barry, To do this, you need trigonometry. For example, suppose the hypotenuse is h and the two sides are a and b. To find the angle between a and the hypotenuse (I'll call it x), notice that the tangent of x = b/a. Work out b/a (it'll just be a number), and then find what angle has this number as its tangent. This is done by taking the arc tangent. On your calculator, it'll be marked as "atan", or "arctan", or "tan^(-1)", or something like that. So the answer is arctan(b/a). Similarly for the other angle. Don't worry about not using the value of h. It, after all, depends on a and b, and the arctangent function takes that into account. You can do a similar thing (using the h) with the arcsin or arccosine functions. I just happened to decide to use the arctangent because I happen to know something about the stability of numerical calculations involving it, but with a "perfect" calculator, it doesn't matter. -Doctor Tom, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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