Anyone able to do maths?

[Graye]

I know how to do this if I have a scientific calculator but as I haven't...

If I have a right angled triangle with two sides 20cm long, what will be the length of the hypotenuse? Blame OH, he's buying up more wood to make a corner cabinet when we get back to the UK...

[Annpan]

The square of the hypotenuse is equal to the square of the other 2 sides....

so 28.3 ..... I think


ETA.... I could be completely wrong

[Graye]

Cheating and doing it with a ruler it comes to around 28cm but I wanted an exact figure. I think 28.3 sounds good on that basis! Well done and thanks...

[Annpan]

Well, my calculator says 28.284271 - so you can use however many decimal points you like

[Thomzo]

Yup - I agree.

Zoe

[Fizzy Izzy]

As a secondary school maths teacher (with a masters degree in maths!) I confirm Annpan's calculation!

By the way, just in case you're stuck in the future, all computers are basically giant calculators and usually have a calculator function somewhere. Mobile phones have calculator functions too. Or plenty of online ones as well. Just google it! Here's one possibility:
http://www.calculator.com/calcs/calc_sci.html

[Graye]

Thank you all! 28.3 it is. As we are talking centimetres and pieces of pine I suspect that will be as precise as he needs.

Now if I could just find something that would help him solve the door/hinge problem he has given himself... I can't even grasp the basic concept of his problem so it's just as well I'm not about to make the cupboard he's working on.

[Rosendula]

I agree with the answer given. I did it using Pythagoras' Theorum I think (?)
A_squared = B_squared + C_squared, A being the hypotenuse

Basically, that means you need to square both sides and add them together. That gives you the square of the hypotenuse, so the square root of that is your answer.

20 squared = 400
20 squared = 400
add them together = 800
Now square root 800 and you get 28.28472

[Millymollymandy]

God you are all so brainy - I don't have a clue what a hypotenuse is. Vaguely remember the name Pythagoras' Theorum from skool but what it was I've no idea. I hated maths.

[Graye]

I got to the 800 bit and then had a mental block about finding the root. I DID pass GCSE Maths but it WAS a very long time ago.

I do remember the maths teaching saying we would find all those formulae useful in later life so I suppose he was right - eventually...

[Millymollymandy]

I've got a Maths O level but how are you supposed to remember any of that b*llocks? (rather like French actually, forgot it the moment I left school!).

[Graye]

I've got a Maths O level but how are you supposed to remember any of that b*llocks? (rather like French actually, forgot it the moment I left school!).

Funny you should say that! When I first typed that message I wrote mental bolock by mistake. I nearly left it because it looked about right...

I did the same with my A level French. All gone! It's coming back a little now but I tend to do a three way translation, French to Spanish (which is much better for me), then to English. Then the same back again! I seem to spend an inordinate amount of time with a pensive look on my face while this is going on! The best is when I get annoyed and don't actually think too hard. My French becomes more fluent but Spanish words creep in so the poor soul who is getting it in the neck has no idea what it's all about!

[Big Al]

God you are all so brainy - I don't have a clue what a hypotenuse is. Vaguely remember the name Pythagoras' Theorum from skool but what it was I've no idea. I hated maths.

I actually used pythag theory to set up my deep beds....... 3,4,5 = a square corner... sad I know butit keeps the fingers out of (some) mischief..

[Green Aura]

When I did maths we had to remember the 3,4,5 and 5,12,13 triangles. Why?

[Fizzy Izzy]

When I did maths we had to remember the 3,4,5 and 5,12,13 triangles. Why?

Well, Big Al mentioned one reason - they can easily be used to check if a triangle has a right angle or not. But the real reason is that that they are commonly used in the exam questions... They are special cases of Pythagoras theorem, that only use whole numbers. Called Pythagorean triples. (just case you ever wanted to know)