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ROSIEBRENDY · May 18, 2009, 02:25 AM

Hi all,
I'm just new to this site. Looking a bit of help with my nightmare Analytical methods assignmnet on trigonometric equations :mad:

Just need a bit of direction to get me on the right track with solving these for 0-360 degrees:

4-7sin(x)=0

15sin^2(A)+sin(A)-2=0

I also have to simplify the following:

sin (x+180degrees)

cos (180degrees-x)

Heeeeeeeeeeeeellllllllllllllllllllllllllllpppppppp ppppppppp before I go insane!

Many thanks :o

Unknown008 · May 18, 2009, 11:20 AM

Hey ROSIEBRNEDY! Welcome to AMDH! :)

Well, you should've posted your question there:

https://www.askmehelpdesk.com/math-sciences/

$4-7sin(x)=0$

$-7sin(x)=-4$

$sin(x)=\frac47$

$(x)=sin^{-1}(\frac47)$

Now press that in your calculator, and you'll get the answer. (note; your values will lie in the all positive quadrant and sine positive quadrant)

$15sin^2(A)+sin(A)-2=0$

Factorise by treating sin(A) as y

$15y^2+y-2=0$

$(3y-1)(5y+2)=0$

$3y-1 = 0$ or $5y+2=0$

Now, replace y by sin(A) and do as you did in the previous question.

$sin (x+180)$ is the same as $-sin(x)$

$cos (180-x)$ is the same as $-cos(x)$

Those, you'll have to learn.

Clough · May 20, 2009, 04:54 PM

Hi, ROSIEBRENDY!

Greetings and WELCOME to the site! I just moved your question that you had posted in Introductions to this forum topic area. Introductions is for people to introduce themselves and we try to not ask questions there.

It can be a little confusing when first learning how to use this site!

I do note, that your question did get one response while it was in Introductions.

We would appreciate it if you would return to Introductions sometime to tell us a little about yourself though, if you
Would be willing to do that.

Thanks!