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# Core 2 ONE mark question... Driving me insane :|

1. Sin pheta + cos pheta = 0
Show that tan pheta = -1

Can someone quickly solve this, so I can move on with my life and look beyond the 30 minutes I've wasted...

2. remember that sin/cos=tan...
remember that sin/cos=tan...
this.

Most likely what' going wrong is that you've forgotten that cancelling out by dividing by something leaves a 1 not a 0. I'm guessing you're arriving at tan(theta) = 0 ?

it's a mistake that I admittedly made quite a few silly times at the start of my maths A-level
4. isn't it theta
5. (Original post by MSI_10)
Sin pheta + cos pheta = 0
Show that tan pheta = -1

Can someone quickly solve this, so I can move on with my life and look beyond the 30 minutes I've wasted...

remember that sin/cos = tan

so use that fact to move the cos pheta across to give

sin = - cos

divide through by -cos

-tan = 1

therefore multiply by -1 to get tan as positive. simples..
6. sin + cos = 0
sin = -cos
sin/cos = -1
tan = -1
7. Hmm thanks all

Is it also possible to multiply the starting equation -1, then end up with tan theta=-1?
sin theta + cos theta = 0

-sin theta - cos theta = 0
-sin theta=1+cos theta
-sin theta/ cos theta = 1
-tan theta=1

tan theta=-1

After posting, I did that and got it right.
Unless it was a fluke
8. (Original post by MSI_10)
Hmm thanks all

Is it also possible to multiply the starting equation -1, then end up with tan theta=-1?
sin theta + cos theta = 0

-sin theta - cos theta = 0
-sin theta=1+cos theta
-sin theta/ cos theta = 1
-tan theta=1

tan theta=-1

After posting, I did that and got it right.
Unless it was a fluke
Where did the 1 come from in the second line? It shouldn't be there. You should just have -sin theta=cos theta
9. (Original post by Gemini92)
Where did the 1 come from in the second line? It shouldn't be there. You should just have -sin theta=cos theta
Oh okay thanks.

So if I didn't make that mistake, it would still work right?

So to summarize, my mistake was that when doing sin theta / cos theta, the right hand side gets a +1 NOT a 0?
10. (Original post by MSI_10)
Oh okay thanks.

So if I didn't make that mistake, it would still work right?

So to summarize, my mistake was that when doing sin theta / cos theta, the right hand side gets a +1 NOT a 0?
Yes.

If you divide cos theta by cos theta you get one

Same as if you divide anything most things by themselves
11. (Original post by wibletg)
Yes.

If you divide cos theta by cos theta you get one

Same as if you divide anything by itself
0/0 doesn't equal 1.
12. (Original post by Mr M)
0/0 doesn't equal 1.
haha, fair point
13. (Original post by Mr M)
0/0 doesn't equal 1.
I was tempted to put most things, infinity divided by infinity isn't one either
14. (Original post by IamBeowulf)
isn't it theta
Nah, it's a new Greek letter this.

15. (Original post by gff)
Nah, it's a new Greek letter this.

That's cool. Unfortunately PRSOM.
16. (Original post by wibletg)
I was tempted to put most things, infinity divided by infinity isn't one either
0/0 isn't infinity, it's solution set is.
17. (Original post by 122025278)
0/0 isn't infinity, it's solution set is.
I don't think he suggested it was.

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