User Name Remember Me? Password

 Algebra Pre-Algebra and Basic Algebra Math Forum

 April 4th, 2008, 06:04 PM #1 Newbie   Joined: Apr 2008 From: Alabama Posts: 2 Thanks: 0 I'm Stumped I want to solve the following equation for b: (b*r)^2 + b^2 = c^2 This equation is similar to the Pythagorean theorem, except that "a" is replaced with "b*r", r being a ratio. I have wasted 5 sheets of paper trying to solve for b, to no avail. If you assume: c = 10 and r = 4/3 Then "b" should yield 6. I feel stupid. Thanks. April 4th, 2008, 06:58 PM #2 Senior Member   Joined: Oct 2007 From: Chicago Posts: 1,701 Thanks: 3 (b*r)^2=(b^2)*(r^2) because exponents distribute over multiplication. so: (b*r)^2+b^2=c^2 b^2*r^2+b^2=c^2 (r^2+1)(b^2)=c^2 And you should be able to take it from there. Cheers. April 5th, 2008, 07:33 AM #3 Newbie   Joined: Apr 2008 From: Alabama Posts: 2 Thanks: 0 thanks, got it Thanks for the tip. I finished up and solved for b. b = sqrt( c^2 / ( r^2 + 1 ) ) I need to read up on my math rules. I'm going to use this formula in a software program that calculates the viewable screen area and DPI resolution of LCD Monitors given the diagonal measure and native screen resolution. I can get the ratio ("r") of any display by dividing the horizontal resolution ("x") by the vertical ("y") and using the diagonal measure ("c") I can determine the height ("b") and width ("b*r") of the monitor and multiply them together to get screen area. And to get DPI, I just use: dpi = sqrt( x^2 + y^2 ) / c I just thought you might me interested in what the formula was for. Thanks for your help.  April 5th, 2008, 11:46 AM #4 Senior Member   Joined: Oct 2007 From: Chicago Posts: 1,701 Thanks: 3 Yeah those rules are things that become intuitive after a while... but it's really easy to forget that they're intuitive... unless you work with set theory or higher algebra, where they aren't guaranteed... Anyway, that's a clever way of handling screen resolution. I assume everything is going to be scaled to fit the screen properly? I suddenly remember why I stick with theoretical CS... April 5th, 2008, 12:15 PM #5 Senior Member   Joined: Apr 2007 Posts: 2,140 Thanks: 0 Re: I'm Stumped (br)² + b² = c² = b²r² + b² = b²(r² + 1) b² = c² / (r² + 1) b(c,r) = ±c / √(r² + 1), where the function is in two variables. b(10, 4/3) = ±10 / √(16/9 + 1) = ±10 / (5 / 3) = ±6 Tags stumped Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Tyrean Algebra 4 August 20th, 2013 06:25 PM tangosix Algebra 2 March 2nd, 2010 10:39 AM yabo2k Advanced Statistics 1 October 27th, 2009 05:41 AM GMNives Algebra 1 May 10th, 2008 02:13 PM malikah Algebra 5 September 11th, 2007 08:38 AM

 Contact - Home - Forums - Cryptocurrency Forum - Top      