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You are not logged in. #1 20051211 17:40:07
stuck on angle between two linesFind the angle between the slopes of the graphs y = x^3 and y = sqrt(x) Last edited by mikau (20051211 17:40:59) A logarithm is just a misspelled algorithm. #2 20051211 18:21:37
Re: stuck on angle between two linesAhh... now I see where 90 comes from. Its because if x^3 = sqrt x, x can equal 1 but it can also equal zero. Last edited by mikau (20051211 18:33:06) A logarithm is just a misspelled algorithm. #3 20051212 13:34:31
Re: stuck on angle between two linesI don't know how your book made the leap of faith to say 90° was definitely a solution. Maybe someone here can show such a proof. #5 20051212 13:53:47
Re: stuck on angle between two linesWell the derivative of x^(1/2) is (1/2)/sqrt(x) set x = 0 and the slope is 0.5/0 which is a vertical line. The derivative is x^3 is 3x^2. When x equals zero it has a value of zero, or a slope of 0/1 which is a horizontal line. So I guess its true. A logarithm is just a misspelled algorithm. #6 20051212 14:23:14
Re: stuck on angle between two linesUh.....sorry. #7 20051212 14:50:24
Re: stuck on angle between two linesBesides, even if it were a vertical line how would you know if it were positive or negative in slope? Would the line be 90° above the x axis or 90° below it? These are questions that the best math minds are still trying to grasp. Perhaps you should contact the publisher of the book that you are using to prove that he/she is correct. #8 20051213 05:35:20
Re: stuck on angle between two linesAre you trying to say that a line with a slope of x/0 is not vertical? Think of the rise over the run. It moves up x units every time it moves over zero units. Then its going straight up. If you prefer to avoid division by zero completely, you could say as the denominator approaches zero, the slope aproaches that of a vertical line, as a limit. If we use 1/infinity as the denominator, then if we call it a vertical line, our error will be infinitly small. A logarithm is just a misspelled algorithm. #9 20051214 14:18:38
Re: stuck on angle between two linesI've been away. I am not disputing that it is generally accepted that the line is vertical when the slope is undefined, but you can not prove it. Say that a wall is has a slope of 3meters/1micrometer. Well, unless you have a very sensitive measuring device you will say that the slope is undefined and that the wall is perfectly vertical. But if the top of the wall were smooth a ball bearing would roll right off. Would you then say that gravity were wrong? 