I'll be around for the next hour or so. Post any questions to the comments (make sure to include the question that you're working on since I don't have the worksheet with me).
ok well i need the tan(345)......i broke it down into 300 + 45 and plugged it in the formula and got negative squareroot of 3 over 1 plus squareroot of 3...now what??
oh u mean on top??? well the tan of 300 is negative squareroot of 3 and the tan of 45 is just 1 so when u multiple the top u should get a negative....i think!! lol
Tawni: your negative sqrt(3) is correct, but you should also have a 1 on top from tan(45), giving you (1-sqrt(3))/(1+sqrt(3)). To rationalize the denominator, you'll need to use the difference of squares and multiply your answer by (1-sqrt(3))/(1-sqrt(3)). Try that and see what you get.
(1-sqrt(3))*(1+sqrt(3)) is a difference of squares. If you can't just see how that would work, try multiplying it out using FOIL. You'll end up with an integer.
It means to use sinx to find cosx and siny to find cosy. Think about it: if you know the sine of an angle, how could you find the cosine of that same angle?
ok well now i got 2 whole worsheets finished...im just still really confused on the one u gave us today and i dont think u are goin to be able to help me over here...i think i will just get confused so i think im just goin to wait till tomorrow! but ok thanks for ur help on the other ones!! see you tomorrow bye!
26 comments:
Ok, Hickman.. cos (x+y) if sin x=5/13 and sin y=4/5..You are supposed to find each exact value
ok well i need the tan(345)......i broke it down into 300 + 45 and plugged it in the formula and got negative squareroot of 3 over 1 plus squareroot of 3...now what??
umm..Ok I did not get that. I got the first square root of three as positive
Use the sum & diff. formula for cos:
cos(x+y)=cosx*cosy-sinx*siny
You know that sinx=5/13 and siny=4/5, so you can substitute that in to get:
cosx*cosy-(5/13)*(4/5)
How can you find cosx & cosy? (Hint: you'll need to use the values for sinx & siny, respectively.)
oh u mean on top??? well the tan of 300 is negative squareroot of 3 and the tan of 45 is just 1 so when u multiple the top u should get a negative....i think!! lol
To Tawni: yes i see that now..
Hickman: Can I just pluge those in? well I did anyways
Tawni:
your negative sqrt(3) is correct, but you should also have a 1 on top from tan(45), giving you (1-sqrt(3))/(1+sqrt(3)).
To rationalize the denominator, you'll need to use the difference of squares and multiply your answer by (1-sqrt(3))/(1-sqrt(3)). Try that and see what you get.
Ashley:
Can you just plug what in? What did you get for cosx and cosy & how did you get them?
I am kinda confused now..Now I have cosx*cosy-(4/13).Can I do that?
so do i just multiply 1 - squareroot of 3 and 1+ squareroot of 3?? bc if i do then i dont see how that gets rid of the squareroot???
That's fine, but how are you going to figure out what cosx is? And cosy?
If I knew then I would do it. You said to use them respectively. Que?
(1-sqrt(3))*(1+sqrt(3)) is a difference of squares. If you can't just see how that would work, try multiplying it out using FOIL. You'll end up with an integer.
that was to Tawni right..
It means to use sinx to find cosx and siny to find cosy. Think about it: if you know the sine of an angle, how could you find the cosine of that same angle?
yes, that was to tawni.
ohh ok gotcha ;)
is it -2??
Tawni: yep.
Tawni:
Now FOIL out the top and simplify.
ok kool!! now how do u do the csc of 915 using sum and difference formulas??
915 is coterminal with 195, so you'll need to find sin(195) using sum and diff. formulas and then take its reciprocal to get csc(195).
so do i use the sin(150+45) in the formula then solve it and then just flip it??
Tawni:
Yes.
ok well now i got 2 whole worsheets finished...im just still really confused on the one u gave us today and i dont think u are goin to be able to help me over here...i think i will just get confused so i think im just goin to wait till tomorrow! but ok thanks for ur help on the other ones!! see you tomorrow bye!
I'm out. See you tomorrow.
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