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- Thread starter Jacob
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I think it should be the other way around. That is, the negative of what you have.

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^I think it should be the other way around. That is, the negative of what you have.

Could you please elaborate more on what you mean by that? I know that the answer is -csc^2x but I want to know the working so it would be easier for me to master it but I'm stuck on the part that I highlighted. This is my first time dealing with cosecant, cotangent & secant

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In the lecture, my lecturer said that this 2 parts (which I marked x) will be canceled out. That makes sense but it didn’t when the next step he wrote the numerator asI think it should be the other way around. That is, the negative of what you have.

Did I get it right?

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Can someone please explain to me what’s happening to the numerator which I highlighted? It’s from my lecture but I don’t understand how it becomessinx sinx sinh- cosx cosh sinx .

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In the lecture, my lecturer said that this 2 parts (which I marked x) will be canceled out. That makes sense but it didn’t when the next step he wrote the numerator assinx sinx sinh - cosx cosh sinx.

Did I get it right?

You mean this is incorrect?Itdoes not! Do the algebra carefully!

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In the lecture, my lecturer said that this 2 parts (which I marked x) will be canceled out. That makes sense but it didn’t when the next step he wrote the numerator assinx sinx sinh - cosx cosh sinx.

Did I get it right?

sin(x) * sin(x) * sin(h) - cos(x) * sin(h) * cos(x) ....,edited

Check it again......

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Sorry about the sloppy work !! Laying in bed and working with "kindle" is just my working. I have to get up and go to a real computer!!This is exactly what my lecturer got. But I’m confused about how he got it. Why it becomes multiply? what happened to the negative sign in front of-sinx.

View attachment 24999

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sin(x) * [cos(x)*cos(h) - sin(x)*sin(h)] - cos(x) * [sin(x)*cos(h) + cos(x)*sin(h)] ..................................multiply and distribute

sin(x) * [cos(x)*cos(h)] - sin(x) * [sin(x)*sin(h)] - cos(x) * [sin(x)*cos(h)] - cos(x)*[cos(x)*sin(h)] .................. cancel appropriate terms

= - sin(x) * [sin(x)*sin(h)] - cos(x)*[cos(x)*sin(h)]

= -sin(h)

A little later I'll delete my previous responses.

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Thank you. It totally make sense right now

sin(x) * [cos(x)*cos(h) - sin(x)*sin(h)] - cos(x) * [sin(x)*cos(h) + cos(x)*sin(h)] ..................................multiply and distribute

sin(x) * [cos(x)*cos(h)] - sin(x) * [sin(x)*sin(h)] - cos(x) * [sin(x)*cos(h)] - cos(x)*[cos(x)*sin(h)] .................. cancel appropriate terms

~~sin(x) * [cos(x)*cos(h)]~~- sin(x) * [sin(x)*sin(h)]~~- cos(x) * [sin(x)*cos(h)]~~- cos(x)*[cos(x)*sin(h)]

= - sin(x) * [sin(x)*sin(h)] - cos(x)*[cos(x)*sin(h)]

= -sin(h)

A little later I'll delete my previous responses.

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Now I hope you see that it is NOTCan someone please explain to me what’s happening to the numerator which I highlighted? It’s from my lecture but I don’t understand how it becomessinx sinx sinh- cosx cosh sinx .

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It's like I have a twin.Sorry about the sloppy work !! Laying in bed and working with "kindle" is just my working. I have to get up and go to a real computer!!

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My Brother....Beer soaked ramblings follow.

It's like I have a twin.

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Yes finally, thanks to you. May I know how you getNow I hope you see that it is NOTsinx sinx sinh- cosx cosh sinx .........

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- sin(x) * [sin(x)*sin(h)] - cos(x)*[cos(x)*sin(h)]Yes finally, thanks to you. May I know how you get

= - sin(x) * [sin(x)*sin(h)] - cos(x)*[cos(x)*sin(h)](This part right here become -sin(h)?

= -sin(h)

= -sin(x)*sin(x)*sin(h) - cos(x) *cos(x)*sin(h)

= -sin

= - [sin

= - [1] * sin(h)

= - sin(h)

Please work with pencil and paper instead of staring at the screen!!

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Sorry, I did work through the problem. But this part- sin(x) * [sin(x)*sin(h)] - cos(x)*[cos(x)*sin(h)]

= -sin(x)*sin(x)*sin(h) - cos(x) *cos(x)*sin(h)

= -sin^{2}(x) * sin(h) - cos^{2}(x) * sin(h)

= - [sin^{2}(x) + cos^{2}(x)] * sin(h)

= - [1] * sin(h)

= - sin(h)

Please work with pencil and paper instead of staring at the screen!!

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Have a closer look at Post #16. It IS negative.