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Trig Identities help

Hey guys,

I'm a little stuck as to how to complete this.

ImageUploadedByStudent Room1475805833.092003.jpg

I've gotten up to (1-cos^2x)/cos^2 - 1 but can't seem to work out the rest


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Reply 1
Try working with the LHS to produce something that you can manipulate using the cos2x\cos^2x
Reply 2
Original post by TheBBQ
Try working with the LHS to produce something that you can manipulate using the cos2x\cos^2x


I have no idea what that's meant to mean. (Self-teaching noob to maths)


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Reply 3
Original post by nemanuel96
I have no idea what that's meant to mean. (Self-teaching noob to maths)


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LHS = Left hand side of the equation.
See what you can do with that first :smile:
Reply 4
Original post by TheBBQ
LHS = Left hand side of the equation.
See what you can do with that first :smile:


Haha I know what that means. The mar scheme's next step is:

1/cos^2x - cos^2x/cos^2x - 1

But I'm not entirely sure how they've managed to do this. ☹️


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Reply 5
Original post by nemanuel96
Hey guys,

I'm a little stuck as to how to complete this.

ImageUploadedByStudent Room1475805833.092003.jpg

I've gotten up to (1-cos^2x)/cos^2 - 1 but can't seem to work out the rest


Posted from TSR Mobile


Just a hint,

x2+32=x+32 \frac{x}{2} + \frac{3}{2} = \frac{x+3}{2}


So use this in reverse
Reply 6
Original post by asinghj
Just a hint,

x2+32=x+32 \frac{x}{2} + \frac{3}{2} = \frac{x+3}{2}


So use this in reverse


Thanks a lot! It makes much more sense now :smile:


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Reply 7
I've gotten up to this question:

ImageUploadedByStudent Room1475851131.470750.jpg

I've so far managed to get up to sinx/cosx + cosx/sinx

The mark scheme's next steps:

ImageUploadedByStudent Room1475851255.361181.jpg

I don't understand how they've transitioned from what I've gotten up to, to getting sinx^2 + cosx^2/sinxcosx. Did they square both numerator and denominator to get to there? :s-smilie:




Posted from TSR Mobile
Original post by nemanuel96
I've gotten up to this question:

ImageUploadedByStudent Room1475851131.470750.jpg

I've so far managed to get up to sinx/cosx + cosx/sinx

The mark scheme's next steps:

ImageUploadedByStudent Room1475851255.361181.jpg

I don't understand how they've transitioned from what I've gotten up to, to getting sinx^2 + cosx^2/sinxcosx. Did they square both numerator and denominator to get to there? :s-smilie:

* * *Posted from TSR Mobile


they just applied the method of adding fractions a/b + c/d = ( ad + bc *)/bd
Reply 9
Original post by the bear
they just applied the method of adding fractions a/b + c/d = ( ad + bc *)/bd


Thank you so much. Haha, my maths is a little rusty.


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