I agree it would be great if i could remember it after the exam. I just know i won't be able to. The 1 week course crams you with years worth of GCSE study and the area part i am asking about is just a small part i am having to study. Hence why i asked my original question.
calculator that works out area?
- Thread starter ivrytwr3
- Start date
Just to actually add something constructive to the thread too..
It looks a bit Noddy, but the "mathsisfun" site is actually quite a well laid out resource for some of the more fundamental aspects of mathematics.
I occasionally look to it myself when I have a blind moment and forget SOHCAHTOA or something
For areas, have a look here, nice online tool-set, with decent descriptions:
http://www.mathsisfun.com/area-calculation-tool.html
It looks a bit Noddy, but the "mathsisfun" site is actually quite a well laid out resource for some of the more fundamental aspects of mathematics.
I occasionally look to it myself when I have a blind moment and forget SOHCAHTOA or something
For areas, have a look here, nice online tool-set, with decent descriptions:
http://www.mathsisfun.com/area-calculation-tool.html
Associate
- Joined
- 19 Dec 2009
- Posts
- 1,749
Unless you're naturally gifted at maths, there's only one thing for it - practice, practice, practice! Having a calculator that tells you the area of a shape is useless as soon as they give you the area of a shape and tell you to find one of its dimensions, especially so if it comes up on a non-calculator exam!
I disagree. This is the case for right angled triangles, height has to be consistently defined. It can't be distance taken perpendicular to an edge of the page, because then when the triangles at an angle your definition fails.
I think that's self explanatory, but if not I'm happy to expand on it.
Last edited:
I really don't understand what you're trying to achieve here...
it is commendable that you want to do this again later in life but if you want to learn basic 'maths' then learn basic maths
if you get a calculator to do this sort of stuff for you then what exactly are you studying other than how to push buttons on a calculator - you're certainly not studying maths. Getting a calculator to perform some calculation you don't understand yourself isn't going to help you at all. The whole point of studying this is so you do understand. You don't need a more advanced calculator you just some more study/help from your tutor (if you have one).
Associate
- Joined
- 11 Sep 2008
- Posts
- 670
- Location
- Northern Ireland
I wouldn't use a calculator that could work the area out for you. At least when I do my exams, we all have to write our calculator model and number on it, im guessing so they can see if the calculator your using is one that does all the heavy lifting for you. I don't think they'd look on it too kindly if they caught you out. But i suppose you could take 2 calculators in with you and write down the model of the normal one, and just use your hardcore one during the exam
No, it doesnt.
As long as you use the right height in relation to what you use as the base.
There are 3 'heights' of a triangle and all of them will give the correct area when used with the right base line.
i'll draw a diagram just now because i dont think i'm explaining it very well.
Ah damn, uploading the last one took me ages. I'm going to have to draw another one too 
I don't think you mean the centre of each line to the opposite corner, but rather a line perpendicular to the side which passes through the opposite corner.
I don't think you mean the centre of each line to the opposite corner, but rather a line perpendicular to the side which passes through the opposite corner.
Last edited:
Yes, sorry, that is what i meant.
This will explain it better:
for each pic, the green line is the height and the red line is the base.
Using a 0.5*base*height formula for each combination will give the same answer each time.
Ok, i think i maybe missed the point you were trying to make.
When you were talking about the orientation on the page, i thot you meant there there was only 1 height of a triangle.
I see what you mean now with that diagram. Obviously the blue line is not the 'height' of the triangle, which may confuse people who are unfamiliar with this stuff.
The latter two are similar really. They still have the height perpendicular to the base, it just so happens that one of the other sides is also perpendicular.
There are always 3 base/height combinations for any triangle.
The green line is coincident with one of the edges of the triangle, but the red one is only coincident with one of the edges when the angle between red/green is 90 degrees. If the red line is the "height" anyway
It would be a fairly easy mistake to think 1/2 green times red would give the area in the above diagram based on the pictures you've shown.
Last edited:
Soldato
- Joined
- 22 Aug 2005
- Posts
- 8,970
- Location
- Clydebank
Sweet jesus....
So your method to work out the area of a right angled triangle is to.... divide it into 2 smaller right angled triangles and work out the area of each one and add them?
Now how do I work out the area of the 2 smaller right angle triangles? Divide them into smaller triangles?
When does it stop ?
So your method to work out the area of a right angled triangle is to.... divide it into 2 smaller right angled triangles and work out the area of each one and add them?
Now how do I work out the area of the 2 smaller right angle triangles? Divide them into smaller triangles?
When does it stop ?
No, it isnt dividing it into smaller triangles, the line across the centre of the triangle is its height. You then put that into the formula 0.5*base*height to get the area.Sweet jesus....
So your method to work out the area of a right angled triangle is to.... divide it into 2 smaller right angled triangles and work out the area of each one and add them?
Now how do I work out the area of the 2 smaller right angle triangles? Divide them into smaller triangles?
When does it stop ?
True, and it's a mistake that i have made more than once
But still, if you have a right-angled triangle most of the time you will have to use the 2 edges as base and height because they will be the dimensions you are given.
Soldato
- Joined
- 22 Aug 2005
- Posts
- 8,970
- Location
- Clydebank
By imagining or drawing this 'height' line such that it intersects a side of the triangle at 90 degrees, you are effectively creating 2 right angled triangles, which as pointed out above is this length (height) * base * 0.5 . When you start with a right angled triangle you don't need to do this...since you already have a right angled triangle
I suppose you could think of it as splitting the triangle into 2 smaller, right-angled triangles if you wanted to but there is no real need to (unless you need to do something like this to get the dimensions - but that is a different matter). The formula will work for any triangle, not just right-angled ones.
The only problem with right angled triangles is that people can become confused with the difference between the height and one of the sides, because they are effectively the same line.