A.Maths - Further Trigo

last SG · 2007-10-28T22:02:36+00:00

ya o lvl method i noe that cos (a+b) = cos a cos b - sin a sin b

eagle SG

okok I skipped a step

tan 5x = tan 2x

5x = arctan (tan 2x) +180, arctan (tan 2x) + 360, and so on....... Mr. Green

eagle SG

see the above post if it answers your question

^tamago^ SG

uncle add maths dun have leh. unless i didn't read this formulae. Laughing

wishboy SG

wth is arctan? Laughing
not in my syllabus
nvm no need to answer this

HyuugaNeji SG

there isnt a need for a formula. This is by observation that tan x repeats itself every 180 degree while sin x and cos x repeats itself every 360 degrees.

^tamago^ SG

inverse tan (the one u know) = atan = arctan.

^tamago^ SG

But not E Maths can use this formulae ah. Okies. I scared lose marks. Laughing

tanjun SG

arc tan refers to inverse function. It is used to prevent confusion with (tan)^-1.

That method is taught in A levels as a shortcut way to solve this type of qns.

eagle SG

this is not by formula. This is by understanding of concepts.

I treated 2x as another normal angle. I always use this method last time during my As, where my maths was really at its peak

HyuugaNeji SG

yeah will lose marks unless you explain yourself well.

tanjun SG

tan 5x = tan 2x

for tan,

X = 180n+ a where a is the principal solution. (learnt at A levels)

5x = 180n + 2x, where n is a real integer.

Thus, 5x = arctan 2x + 180, arctan 2x + 360 and so on.

3x = 180n.

For sin,

X = 180n + (-1)^n (a) (n is a real integer)

For cos,

X = 360n + a or 360n - a (n is a real integer)

gd to know as this general formula enables you to find all the values within any range given.

eagle SG

Now that you mention it, I remember Laughing

But then, by doing it without remembering this shows the importance of understanding the concepts as compared to memorizing the formulae Wink

HyuugaNeji SG

^tamago^, looking at your standards, i think you will confirm score A1 for your E Maths de. Just remember E. Maths can be more tedious than A Maths but it is definitely easier.

I think your maths is so much better than me when i was at your age taking O level. O levels Maths back then was so easy that it is almost laughable. Till now, i still believe i got 100/100 for my E maths paper 1 and 2 and A maths paper 1 and 2 lol. I got A1 for both subjects.

As for A level, i didnt think i do well for my Further Maths and Maths C. I think i lost over 20marks for F Maths and 10+ marks for Maths C. Deep now i thought i would be getting B for both modules. But still got A for both exams Smile

As for uni maths, I am getting owned=(

eagle SG

you taking maths or engineering or other degree in uni?

HyuugaNeji SG

Dont wanna say. Laughing

tanjun SG

lol. This idea just pops in my mind when you do it the shortcut way. My teacher used to highlight this in lectures last time telling us don't waste time expanding the tan function. Formulas can be remembered provided that you understand how the formula originates, how it is created.

For example, for the three general formulae created above, they are created to suit the CAST that we have learnt in O levels for trigo.

^tamago^ SG

yeah i scored A1 for both. personally i find E Maths more of understanding of concept and drawing on graph papers, while for A Maths I could be writing lines and lines of mathematical statements away which I preferred. Laughing

yes, it is possible to get 100 for E Maths and A Maths, but not for Maths C and F Maths. uni maths is horrible. Crying or Very sad

HyuugaNeji SG

You at uni also?

eagle SG

yeah

my max score for F maths was only 98 Sad That was during my promos..... Really cannot get 100...

eagle SG

unless you are taking maths at higher levels in uni, I don't see why uni year 1 maths are that hard Rolling Eyes

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