Trigonometry Problem

[Halil]

Okay guys,

I started doing trigonometry chapter of the book and have encountered a type of question that I just do not know how to solve.

Here it is:

If Sin(x) =0.3, cos(a)= 0.5 and tan(b)=2.4, and x,a and b are in the first quadrant,

find:
1) sin(pie-a)
2)cos(pie-x)

The other questions are like sin(2pie-x), as in, it uses x for sin, a for cos and b for tan but the two above don't use their letter.
I did the rest of the unit and had no problem but these two questions which are meant to be the easy ones are concerning me.

Any help?

[vea]

You can use the identity to calculate the values of and

eg.





(reject the negative because x is in the first quadrant, cos is positive in the first quadrant)

So (cos is negative in the 2nd quadrant)

[Halil]

Thanks for that, do not know why i could not think of it at the time.
Another basic question.
How do you find the basic angle for, lets say sin(x)=0.7?
Can you show me the method please

[brightsky]

You can't, as far as methods is concerned. Unless you mean sin^(-1)(0.7).

[Halil]

In the workbook It says find all the solutions to sin(x)=0.7 within the domain of [0,2pie]

And it uses 0.7714 or something as the angle.
So the solutions are 0.7714 and pie-0.7714 which is 2.370.


I hate it when the book skips small details like this. I think they expect us to know it from previous years, but I can not remember anything like that. I need to find out because there are quite a few questions asked in the same way.

[Halil]

Never mind, found it. It is sin^-1(0.7) like you said.

[BubbleWrapMan]

Whenever I get questions like these, I do two things

1) Convert the decimal number to a fraction
2) Draw a triangle using the numerator and denominator for appropriate sides

For example if sin(x) = 0.3 = 3/10, let the hypotenuse be 10 while the opposite is 3. Then just use Pythagoras' theorem to work out the adjacent, then you can pretty much do what you want with it.

Additionally, remember ASTC, and you can't get these wrong.

[Respect]

Never mind, found it. It is sin^-1(0.7) like you said.

halil were not even upto trig u goose, were still in log func. u goose

[Halil]

Its called moving ahead of class and that is what you do if your aiming for high in Methods

[Respect]

LMAOO ISIK BOYSSSSSSSSS

shut up,abi school sux up captain.

[Respect]

LMAOO ISIK BOYSSSSSSSSS

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[isik.college]

ayri FIK, give us our common room!

[Respect]

ayri FIK, give us our common room!

r0fl!!! best user name... hehehehe wonder what _______ and freinds think about it hahah

[Abdulhai]

lmao hassanain and tarek two of the biggest scums in the world.
Your both idiots.

[taiga]

oi guys shut up and take your useless chat to myspace