If , show that

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- Jan 28th 2010, 01:38 AMPunchTangents
If , show that

- Jan 28th 2010, 04:47 AMGrandad
- Jan 28th 2010, 11:58 PMPunch
Thanks but I don't understand how to relate them..

- Jan 29th 2010, 12:36 AMGrandad
Hello Punch

Here's the last bit, then:

Grandad - Jan 30th 2010, 06:12 AMPunch
It is all so confusing... I have tried to combine the 2 posts but it makes no sense to me.

If , show that

How about telling me the idea of solving this question? Is it about changing everything in terms of A? - Jan 30th 2010, 10:22 AMGrandad
Hello PunchI'm not sure what you mean by this. You were asked to show that if a certain statement was true (namely, ) then another statement follows (namely, ).

I have done this by starting with the equation and ending with the equation .

Putting together my two posts, we get:

Grandad - Jan 30th 2010, 07:18 PMPunch
I don't understand

- Jan 30th 2010, 07:24 PMProve It
Expand the brackets and then add to both sides...

- Feb 1st 2010, 05:03 AMPunch
To solve this question, I have to relate it to the tangent additional formulae.

- Feb 1st 2010, 06:03 AMGrandad
- Feb 3rd 2010, 04:05 AMPunch
- Feb 3rd 2010, 04:24 AMGrandad
Hello PunchThanks for the concession to my eyesight!

As far as your question is concerned, I'm afraid that experience - practice, practice, practice - is the only answer: just like learning to play a musical instrument.

There are just so many trig formulae, it's impossible to give any simple answer as to what to use and when. Since there are so many formulae, I always found it helpful myself - and so I taught my students - to recite the formulae aloud that I was trying to learn. Write them on Post-It stickers, and stick them up in places where you'll see them while you're doing something else - something that doesn't require much brain power (peeling potatoes, painting a fence, listening to your girlfriend, etc, etc) and recite them over and over. (Perhaps I wasn't really serious about the girlfriend bit...)

Grandad