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 November 20th, 2011, 06:59 AM #1 Senior Member   Joined: Jun 2011 Posts: 154 Thanks: 0 Simple, not so simple question about areas of triangles I keep getting mixed answers from tutors when asking this question, so if someone could please help me out it would help tremendously. I am wondering how to find the area of a non right triangle, given the lengths of 2 sides and the angle in between them. I know the formula 1/2(b)(h)(sinx) I wish I could draw the triangle to show why I am so confused, but apparently my definition of the word "height" and other people's is two different things. The triangle I have is triangle DEF DE = 7 feet EF = 5 feet and angle E = 135 degrees I was told to simply plug the numbers into the formula, which would be: 1/2(7)(5)(sin 135 degrees -- ?2/2) which calculates to 32?2/4 this is assuming that the height is 5 feet. The only problem I have with that assumption is that the side EF is not a vertical line, it is actually pointing out 45 degrees, therefore it would seem to me that the actual height is the distance between angle F and the base. I hope that I explained this clearly enough so that someone can understand what I am asking and help me out with this, because I really need to get this figured out ASAP. Thanks to whoever can help me. November 20th, 2011, 08:14 AM #2 Global Moderator   Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,958 Thanks: 1146 Math Focus: Elementary mathematics and beyond Re: Simple, not so simple question about areas of triangles Make a diagram. The height is 5 * sin(135) (this follows from the definition of the sine), assuming the base is DE. sin(180 - x) = sin(x), so sin(135) = sin(180 - 135) = sin(45), if you're wondering why a 45� angle isn't used. Tags areas, question, simple, triangles 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 shunya Algebra 2 March 9th, 2014 06:26 PM lemonpanna Abstract Algebra 9 July 23rd, 2013 05:38 PM Deaven Calculus 5 April 28th, 2013 12:50 PM playmebaby Advanced Statistics 3 May 2nd, 2012 10:19 AM idolorand Algebra 2 April 29th, 2010 11:31 AM

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