Sums to products, products to sums (1 Viewer)

[needpapers]

Are we required to memorise them for the exam, or will memorising them just be a waste of time?

 

[conics2008]

yes

 

[lolokay]

is this the trig ones? you probably wouldn't need to memorise them, since you should be able figure them out in like 10 seconds (well, won't take long at least), but I suppose it wouldn't hurt to learn them off by heart

 

[tacogym27101990]

Are we required to memorise them for the exam, or will memorising them just be a waste of time?

its not part of the syllabus,
so they'd have to walk us through it id believe
but it never hurts to know too much

 

[Trebla]

Are we required to memorise them for the exam, or will memorising them just be a waste of time?

You are not required to memorise them. Most questions usually ask you to prove them. Others allow you to assume them (with the formula actually given) when proving something else.

 

[vds700]

It says specificallly in the 3 unit syllabus that the product to sum and sum to profuct formulas are NOT in the syllabus, so I reckon they'd ask you to prove it if it was needed in a question.

 

[Affinity]

I am under the impression that it is in the syllabus for 4unit.

 

[shaon0]

I am under the impression that it is in the syllabus for 4unit.

what do you mean by sum to product and product to sum?

 

[ronnknee]

I don't think you're required to memorise as you can easily derive them in less than a minute. Like what Trebla said, they would normally ask you to prove it first then apply it in another question

 

[machiavel]

Stuff whether they are in the syllabus or not. I would definitely memorise them for use in integration with trig fns. It's dead easy anyway: sin uses different fns in each product, so use the same sign, whereas cos uses the same fns and different signs.
Maybe this makes more sens if you look at an example:
sin sum --> sin(A+B) = sinAcosB + sinBcosA <-- two fns in each product so same sign
cos sum --> cos(A-B) = cosAcosB + sinAsinB <--one fn in each product so switch sign.
Don't bother memorising them before the 3U exam, but do it before the 4U.