ekko20six Posted September 1, 2008 Share Posted September 1, 2008 Ok all, i have a maths question for you which all the details are attached in the picture... basically you work the area of a triangle and get area a then you work out the areas of the shapes inside (4 small triangles and one rectangle) and instead of getting area a you get area b. why do you get different answers? Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/ Share on other sites More sharing options...
monkey13 Posted September 1, 2008 Share Posted September 1, 2008 Because the overall shape isn't a triangle. If we calculate the angle of B between the hypotenuse and the base ( x = tan^-1(5/3)) we get 59.03. The angle of C between the base and the hypotenuse should be the same. ( x = tan^-1(8/5)) but it isn't its 57.99. So it's not a triangle. This is confirmed if we try to calculate the angle in triangle B using the whole shape height and half the base. ( x = tan^-1(13/8)) We get 58.39. They should all get the same angle so it's not a triangle. Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726876 Share on other sites More sharing options...
xendrome Posted September 1, 2008 Share Posted September 1, 2008 ^Pwned..... Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726900 Share on other sites More sharing options...
Keito Posted September 1, 2008 Share Posted September 1, 2008 Because the overall shape isn't a triangle. If we calculate the angle of B between the hypotenuse and the base ( x = tan^-1(5/3)) we get 59.03. The angle of C between the base and the hypotenuse should be the same. ( x = tan^-1(8/5)) but it isn't its 57.99. So it's not a triangle. This is confirmed if we try to calculate the angle in triangle B using the whole shape height and half the base. ( x = tan^-1(13/8)) We get 58.39. They should all get the same angle so it's not a triangle. ehhrm, I'm certain your math is correct and all, but isn't a triangle just like... something with three corners? Non-native english speaker here, I was in the perception that a triangle is antyhing with 3 corners :p sort of like a rectangle having 4 and such (and a square having to be square...yet still a rectangle) Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726904 Share on other sites More sharing options...
monkey13 Posted September 1, 2008 Share Posted September 1, 2008 Yeah a triangle is something with three corners but this shape has five. Top, bottom left, bottom right, where the top of B meets the bottom left of C and where the top of E meets the bottom right of E. It's only a one degree change in angle which makes the top of this shape larger than it should be if it was a triangle hence the differences in areas. Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726914 Share on other sites More sharing options...
Eoin Posted September 1, 2008 Share Posted September 1, 2008 You are correct that anything with three corners is a triangle, but Keito's point is that the shape actually has 5 corners, two are just too subtle to see in the image shown. edit- beaten to it :) Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726916 Share on other sites More sharing options...
Keito Posted September 1, 2008 Share Posted September 1, 2008 Need to change the names Eoin ;) but I get it :) Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589726934 Share on other sites More sharing options...
MillionVoltss Posted September 1, 2008 Share Posted September 1, 2008 good idea for a topic, really hard question or problem or what am I then next person ha to answer and put there question in. Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589727246 Share on other sites More sharing options...
monkey13 Posted September 3, 2008 Share Posted September 3, 2008 Now come on jasperau. Do I not get any kind of confirmation that I'm right? Maybe I'm not? No acknowledgement or thanks? Either I helped you with something or you were trying to stump everyone and didn't. Which was it? Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589735240 Share on other sites More sharing options...
Dick Montage Posted September 3, 2008 Share Posted September 3, 2008 I'm over-emphasizing it here to show - but this is not a triangle. Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589735278 Share on other sites More sharing options...
ekko20six Posted September 8, 2008 Author Share Posted September 8, 2008 Now come on jasperau. Do I not get any kind of confirmation that I'm right? Maybe I'm not? No acknowledgement or thanks? Either I helped you with something or you were trying to stump everyone and didn't. Which was it? lol sorry there, i forgot to come back and comment. well the thing is, this is a question for year 8 maths in western OZ, so they have not learnt how to use SIN, COS or TAN yet... i get what ur saying with the 'its not a real triangle' but i am wondering if there is a simpler explanation??? any thoughts...? Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589756774 Share on other sites More sharing options...
monkey13 Posted September 8, 2008 Share Posted September 8, 2008 Ah ok is that about 13-14 years old? I thought I'd learnt some trigonometric functions by then but maybe it was a bit later. Anyway you can do it another way. Triangles B and C should have all the same internal angles. So they are just different sizes of the same triangle. Taking the difference between the heights of B and C (8/5) C is 1.6 times higher than B. If B was just a smaller version of C then the base of C (5) would be 1.6 times the base of B(3) but it isn't. (3*1.6 = 4.8). So they don't have the same internal angles so overall it's not a triangle. Link to comment https://www.neowin.net/forum/topic/664244-weird-triangle/#findComment-589757636 Share on other sites More sharing options...
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