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# C3 trig question watch

1. Given that 5 sinxcosy + 4cosxsiny=0 and that cotx=2 find the value of coty

really confused about even how to start this, many thanks
2. cosx/sinx = cotx....that's the only real hint I can give....It wants you to get it in that that form and use that value.
3. Right, think I've got it.

Try and combine the sines and cosines into tans. Then you can rearrange to get "tan x = ?".

Any idea where to go from there?
4. Right so I've divided by sin x to give

5cosy/sinx +8siny/sinx = 0

but now what?

x everything by sinx?
5. cosx/sinx = cotx......cosxsiny/sinx = cotx.siny = 2siny....I think that's how they want you to approach it.
6. (Original post by joestevens2092)
Right so I've divided by sin x to give

5cosy/sinx +8siny/sinx = 0

but now what?

x everything by sinx?
Multiplying everything by sin x will just get you back to where you started, won't it?

This is how I approached it:

5 sin x cos y + 4 cos x sin y = 0

5 sin x cos y = -4 cos x sin y

5 (sin x/cos x) = -4 (sin y/cos y)

As someone else said, sin/cos = tan, and 1/tan (or cos/sin) = cot.
7. (Original post by Tortious)
Right, think I've got it.

Try and combine the sines and cosines into tans. Then you can rearrange to get "tan x = ?".

Any idea where to go from there?
Could I please send you my PS?

My tutor claims that it shows no enthusiasm for Law... I disagree with him though.
8. We don't need tan, all we need is cot, which is 1/tan.....don't forget that!
9. (Original post by Doughnuts!!)
Could I please send you my PS?

My tutor claims that it shows no enthusiasm for Law... I disagree with him though.
Are you stalking me, or did you just search my post history?

Of course you can. Is it "short enough" to PM me, or would you prefer my email address?

10. (Original post by Tortious)
Are you stalking me, or did you just search my post history?

Of course you can. Is it "short enough" to PM me, or would you prefer my email address?

I frequent the Maths forums quite a bit! When I saw your post on here I decided to ask cos my tutor trashed it.

HONESTLY! Oh, and it would be better to email it to you tbh!

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Updated: September 27, 2010
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