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Segar Rogers
@segarrogers.bsky.social
Teacher. Maths. Secondary. Edinburgh. Old enough to remember chalk.
187 followers194 following203 posts
SRsegarrogers.bsky.social

Just lovely!

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SRsegarrogers.bsky.social

Feels more like ‘Today we have done (drum roll) focusing!!’

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SRsegarrogers.bsky.social

But you’re not really memorising more triangles my way, you’re just remembering the relationships required to build the triangles you need. I think that’s different.

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SRsegarrogers.bsky.social

Ah I see. I struggle with ‘memorise this’ in my own learning. I always have to build what I need. My ‘on the fly’ usually involves me having to re-build knowledge. I agree the ratio ‘special triangles’ are more efficient (if you can remember them!) … it’s just that I struggle working that way.

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SRsegarrogers.bsky.social

But you're thinking in ratios still ;-) For me, tan is a length. • tan 45°: Draw out tan 45° ...(base =1, angle 45°) ... realise that 45° ⇒ the vertical will be 1 too. • tan 60°: Draw out tan 60° ... (base =1, angle 60°) ... realise you can scale a sin 60° triangle. No ratios in sight :-)

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SRsegarrogers.bsky.social

The lineTrig ones are what you’d use on a unit circle to build, say, a basic sine table of 24 values; they’re your starting point. I don’t think of them as ‘special’ to be honest. And obviously the ratioTrig ones are just scaled versions of these to give nice numbers. That’s how I see it.

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SRsegarrogers.bsky.social

As for the ‘special’ triangles, well, they’re specific to trig-as-ratios … the ‘special’ triangles for trig-as-lengths are different!

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SRsegarrogers.bsky.social

If you start trig from a similar triangles perspective (with sin, cos, tan as lengths) then the multipliers are just a nice procedural framework that sits on top of the maths.

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SRsegarrogers.bsky.social

So for 14 ÷ 3 = 4 rem 2 you’d say ‘we’re left with 2 out of the 3 we’d need to make a whole … and 2 out of 3 is ⅔’ ? I could get use to that :-)

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SRsegarrogers.bsky.social

Good question. So 1 is left over. • 2 goes into that 1 ‘half times’. • ½ of 2 goes into the leftover 1. • That 1 still needs to be divided by 2 … and 1 ÷ 2 is a ½. Hmm, not so easy so say! I find myself swithering between partitive and quotative thinking. I tend to say the third option.

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SR
Segar Rogers
@segarrogers.bsky.social
Teacher. Maths. Secondary. Edinburgh. Old enough to remember chalk.
187 followers194 following203 posts