E mathematics for O's. Revision for trigonometry.
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Trigonometry
Sine, Cosine and Tangent
using toa, cah, soh
toa --> tan = opp/adj
cah --> cos = adj/hyp
soh --> sin = opp/hyp
opp, adj and hyp are the 3 line that form a triangle
For this triangle , ACB is a right angle.
Different angles have different Sine, Cosine and Tangent...
As you can see, using toa cah soh to solve can only be used on a right angled triangle...
ABC is a right angle triangle...
If the question ask, "Find Angle A"
You will need to find what is Tan A first then find what is A
Then you will have to used the tangent formula toa, tan = opp/adj.
the opp line for A is a, the hyp line is c, the adj is b...
How to tell which line is which?
Opp, Opposite... as the name say the one that is opposite the angle...
Hyp, Hypotenuse... The longest one... This is opposite the right angle
Adj, Adjacent... Also as the name says, "lying near, close" which mean this line will touch the angle given...
Hyp and Adj is different... Hyp is the longest one, while Adj is the other one which touch the angle... Hyp will also touch the angle...
The fomular toa, tan = opp/adj.
Tan A = opp/adj
Tan A = a/b
A = tan^-1 a/b (you need a calculator for this)
Tan^-1 mean Tan to the power of -1, which mean tan inverse...
Well thats all...
It is the same for other Formula or Angles...
Any question can ask me ^^
Maths is my best subject ^^ -
Trigonometry The Sine rule.
Sine rule:
a/sinA = b/sinB = c/sinC
Well you need to used calculator for this too...
A----> the angle
a ---> the line
they are different.
so if they ask you to find the angle or length, just sub in and do the algebra ^^ -
An example on Sine rule... -
The 'cosine rule' ...
a² = b² + c² - 2bc cosA
b² = a² + c² - 2ac cosB
c² = b² + a² - 2ba cosC
well the same... just sub in and you can find whatever you want...
Note: a sin,cos,tan always come after an angle and will never a line!
that mean will always be a degree and not cm... -
You can find more info on this page
http://www.teacherschoice.com.au/Maths_Library/Trigonometry/solve_trig_SSS.htm
Thats all...
Trigo lesson over... -
gd job pika!
i hope more of these threads will come up in homework forum~ -
Although it's the same, but it'll shorten the revision time by using this immediate-derived formula.
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e.maths for o lvl got include secant, cosecant and cotangent?
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No.Originally posted by wishboy:e.maths for o lvl got include secant, cosecant and cotangent?
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if yes siao liao... cus i dun understand that >.<Originally posted by Darkness_hacker99:No. -
me too >.<Originally posted by popikachu:if yes siao liao... cus i dun understand that >.< -
If you got learn A Maths... anyway, this topic is a curse to me. I fail any topics related to geometry.
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heng nv include...
anyway those 3 trigo ratio beri difficult meh