Shoutbox

I had this problem in a test and I didn't know how to do it. I'm in Year 9

it's right angle trigonomotry.

this example uses Cosine (Adjacent and Hypotinuse)

so you basically put in the calculator Cos(-1) (a/3a)

understand?

ahh yess Thankyou! I had a mind blank in the test. I hope i did well... it was our yearlies. but i don't have an A on my calculator.

perhaps this will aid him in remembering it better

soh cah toa

sine=opposite/hypotenuse
cosine=adjascent/hypotenuse
tangent=opposite/adjascent

hope this helps .

the A is just a variable. It cancels out of this equation.

quote:

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Originally posted by ipab
perhaps this will aid him in remembering it better

soh cah toa

sine=opposite/hypotenuse
cosine=adjascent/hypotenuse
tangent=opposite/adjascent

hope this helps .

the A is just a variable. It cancels out of this equation.

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I have a better way ... well i had two but i cant remember one as i never used it ....

OAO
HHA

Sine cosine Tan

And we all know the other 3 are reciprocals of the first three

Say it like "O-A-O upon (divided by) H-H-A"

Hence Sine = O/H; Cosine = A/H and Tan (Tangent) = O/A

So obviously for Cosecant, Secant and Cotangent read it the other way round (ie the bottom 3 first .....) or just remember Cosecant = 1/Sine



Sin (2x) = 2 Sin (x) . Cos (x)
tanh^(-1) (x) = (1/2) * log [(1+x)/(1-x)]


</trigonometry mode>

While we're at it, a/3a = 1/3
cos^-1(1/3) = 70.5288 = x

can u calculators at school? thats cool, we cant.

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Originally posted by Rubber Stamp
can u calculators at school? thats cool, we cant.

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Hehe i know ..... thats why the students in our schools are good at maths (thats what i have heard)
What i have heard is that usually students from india score well in their maths sat's

I can use a calculator now that im in engineering

We have always been allowed to use a calculator, only on questions that are caculator-friendly though .

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Originally posted by traxor
We have always been allowed to use a calculator, only on questions that are caculator-friendly though .

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The thing is that we are used to having non calculator sums (always having the angle as 0, 30, 45 or 90 .... or well .... continue that series in every quadrant) so when if we goto engineering (like i did) we have a calculator in our hands then we work faster cause we use our brains as well for the simple calculations in that series ..... but people say not to get too dependent on it .... cause then you become slower at mental mathematics cause by the end of 12th grade the best students are so good that they can tell you the answers to integration which will take 2 pages without writing a word (mental calculus) ..... pfft ..... now im lazy i do my integration on my calculator so i aint as good at mental calculus as i was then

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quote:

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Originally posted by Shervin.B
but i don't have an A on my calculator.

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Which calculator are you on Shervin ??? Higher scientific calculators can directly solve 1 variable equations. For 2 and 3 variable equations there are modes .... my calculator doesnt go higher than that.
Im using a Casio fx-991MS