GCSE Maths Question

Yep. It's ratios (scale factors, as they're called when applied to shapes), this is a question from one of the exercise books at school. :p

I've actually got it down in one of my maths books, I'd take a photo, but that would be sad and it's already been answered.
 
Some dodgy maths going on in this thread :p

Just similar triangles, no need for trigonometric ratios here.
 
Smithy said:
ooh i like these :D

ok, because the lines AB and DE are parallel, its satisfactory to say that the two triangles are 'similar'. Meaning one is a ratio of the other.

deviding any one side by its respective similar side on the other triangle gives us this ratio.

9/6 = 1.5. So ratio is 1.5.

8x1.5 = 12, CE = 12.

13.5 / 1.5 = 9, BC = 9.

:)
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Quoted again, in an attempt to drown out all the idiots.
 
Violent-J said:
It's a trigonometry question, I only done my GCSE maths this time last year and got a b, but i forgot it all already lol.

It's to do with Syn, Cos, Tan or SOH CAH TOA as my teacher used to say.

syn is opposite over hypotenuse

cos is adjacent over hypotenuse

tan is opposite over adjacent

Something like that...
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Trig only works with right angled triangles
 
Energize said:
Trig only works with right angled triangles
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That is a lie. Although I concede that perhaps at GCSE level you haven't learnt to do it with non-right-angled triangles... surely you've learnt the sine rule, though?

a/sinA = b/sinB = c/sinC
 
Arcade Fire said:
That is a lie. Although I concede that perhaps at GCSE level you haven't learnt to do it with non-right-angled triangles... surely you've learnt the sine rule, though?

a/sinA = b/sinB = c/sinC
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I didnt realise the sine rule was trigonemtery.
 
Arcade Fire said:
That is a lie. Although I concede that perhaps at GCSE level you haven't learnt to do it with non-right-angled triangles... surely you've learnt the sine rule, though?

a/sinA = b/sinB = c/sinC
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From what I remember, both the sine and cosine rules were taught at GCSE. and that the area of a triangle was 0.5×ab×sinC
 
crunchman said:
It's like that with most exam boards if you got full marks in the coursework and are doing the higher tier.
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Coursework is usually 20% in maths. Youd need 100% in the coursework and all the modular tests to only need 20% for a C in the final exam.
 
well gcses must have changed a bit :s

i did the higher paper and managed an A 3 years ago and seriously have never used ratios to solve triangles :o not even at college :eek:
 
Maths, the majority of it the largest waste of time know to man.

If you aint doing A level maths or physics or some whacky crap dont bother, do what i did many moons ago. coast for an easy "C" and concentrate on something useful like french or german :)
 
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