Question

Need help with precalculus will give owl bucks

Answer 1

Hello matlee, I really want to help, but I probably won't know, but I want to give it a try. :)

Answer 2

You know what pie is? The number?

Answer 3

its 3.14

Answer 4

yes

Answer 5

Ok so now you plug that in. so 11*pie

Answer 6

that will be over 16

Answer 7

Ok i understand, but what should i do with cos and sin

Answer 8

Cos, just means opposite, therefore you would do opposite.

Answer 9

Sorry I meant sin is opposite and cosine is adjacent

Answer 10

so i need to figure out all the Pies before i move on

Answer 11

Yes

Answer 12

for this problem you will want to use the angle sum and angle difference formulas

Answer 13

ok

Answer 14

true, but for now he finds the pie, i belive tell me if im wrong

Answer 15

https://www.mathsisfun.com/sine-cosine-tangent.html


might help

Answer 16

recall that, for
\(\large \cos(\alpha+\beta)=\cos(\alpha)\cos(\beta)-\sin(\alpha)\sin(\beta)\)

Answer 17

That looks good

Answer 18

So this is the formula?

Answer 19

yeah. Note that alpha is pi/16 and beta is 11pi/16

Answer 20

so, tell me what you get when you reduce the right hand side to the left hand side?

Answer 21

wait s o do i have to get the actual decimals

Answer 22

No.

Answer 23

\(\large \cos(\alpha+\beta)=\cos(\alpha)\cos(\beta)-\sin(\alpha)\sin(\beta)\)
\(\large \cos(?+?)=\cos(\pi/16)\cos(11\pi/16)-\sin(\pi/16)\sin(11\pi/16)\)

Answer 24

what are the two question marks?

Answer 25

pi/16 11pi/16

Answer 26

yah so then you get
\(\large \cos(\pi/16+11\pi/16)\)
combine and simplify.

Answer 27

yup

Answer 28

12pi/16

Answer 29

3pi/4

Answer 30

so pie=what?

Answer 31

and cos(3pi/4) equals what?

Answer 32

just plugin the pie with the 3, then you might get it.

Answer 33

is that right

Answer 34

yup.
try if you can to learn the unit circle sometime; this will prove very useful if you take calculus.
but that is correct.

Answer 35

yea

Answer 36

should i write it in decimal? and ok

Answer 37

No. You were told to find the EXACT value. Any decimal approximation of the EXACT value is NOT correct.

Answer 38

wait

Answer 39

so your answer is -1/sqrt(2)=-sqrt(2)/2

Answer 40

Oh I see what you mean

Answer 41

Ok thank u

Answer 42

no problem

Answer 43

its not -1/sqrt2?

Answer 44

Sorry, for the little help. I really struggle myself.

Answer 45

Thats alright thanks anyways

Answer 46

lol np

Answer 47

ive been here for 4 hours, 1 last question to go

Answer 48

and this is just a test review but i need to study

Answer 49

It is, but generally speaking we rewrite it in the form such that the square root is on top. so in this case
\(\Large \frac{-1}{\sqrt{2}}=\frac{-1}{\sqrt{2}}*\frac{\sqrt{2}}{\sqrt{2}}=\frac{-\sqrt{2}}{2}\)

Answer 50

(this is called rationalizing the denominator)

Answer 51

mathway did you sort of understand what inkyvoyd helped you with?

Answer 52

Hopefully you did, I mean good luck with the test.

Answer 53

So do i write sqrt-2/2 or just the whole equation. Also thank you mark i hope i do well too

Answer 54

Well, its better to show the whole equation.

Answer 55

well you want to show your work, but the end result is -sqrt(2)/2

Answer 56

Yea, you know how some teachers are.

Answer 57

Ok wait i have 1 more question. I have to do this question with a calculator how would iget a fraction

Answer 58

Oh on a calculator good point.

Answer 59

maybe just decimals

Answer 60

It will be just decimals.

Answer 61

yh

Answer 62

hmm... that doesn't make much sense. you can't really do a question with an EXACT value on a calculator if the number isn't rational

Answer 63

Some calculators will do the work, but most won't.

Answer 64

I tihnk the teacher will take decimals,

Answer 65

Yea I am pretty sure

Answer 66

I mean how else

Answer 67

I don't think so, but you can check with your teacher.

Answer 68

mark did u get urs

Answer 69

Yea thanks! That was my first time earning one lol. :)

Answer 70

@matlee I really hope you get an A on your test, is it a final or just a normal test?

Answer 71

thanks matlee - best of luck :)

Answer 72

Np, thanks. I can probaly get an A now. normal test

Answer 73

Np

Answer 74

Oh ok good, because I was really worried lol. Still you better get an A my friend. :)

Answer 75

Tell me how it was when you take it. Good luck