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# trig watch

1. Given that
8 tan x - 3 cos x = 0
show that
3 sin^x + 8 sinx - 3 = 0
2. (Original post by Katiekat2000)
Given that
8 tan x - 3 cos x = 0
show that
3 sin^x + 8 sinx - 3 = 0
Start by changing tan(x) to sin(x)/cos(x). Then multiply the equation by cos(x). Please post your working if you get stuck.
3. (Original post by notnek)
Start by changing tan(x) to sin(x)/cos(x). Then multiply the equation by cos(x). Please post your working if you get stuck.
thanks so much
i did what you said and came up with sinx - 3cos^2x = 0
i then subbed 1 - sin^2x into where the 3cos^2x is
i was wondering if this was right and where to get the -3 from
4. (Original post by Katiekat2000)
thanks so much
i did what you said and came up with sinx - 3cos^2x = 0
i then subbed 1 - sin^2x into where the 3cos^2x is
i was wondering if this was right and where to get the -3 from
Your method looks good but It should be

and that becomes

If you expand the bracket you should see where the comes from.
5. (Original post by notnek)
Your method looks good but It should be

and that becomes

If you expand the bracket you should see where the comes from.
that makes so much more sense now i didn't realize you carried the intergers aswell. thanks

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