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trigonometry without a calculator

I have a mock maths gcse and on my revision list for non calculator I have basic trigonometry and was wondering if you could do it without a calculator as I am struggling to find a formulae that is without a calculator.
Original post by jess2016
I have a mock maths gcse and on my revision list for non calculator I have basic trigonometry and was wondering if you could do it without a calculator as I am struggling to find a formulae that is without a calculator.


Pythagoras' theorem might come up - you might be expected to give answers as surds.
Original post by jess2016
I have a mock maths gcse and on my revision list for non calculator I have basic trigonometry and was wondering if you could do it without a calculator as I am struggling to find a formulae that is without a calculator.


If you really understand what the definitions of sine and cosine are then yes you can work out the sine/cosine/any other trig function of any multiple of 30 degrees or 45 degrees from scratch (with any memorisation whatsoever) using the unit circle. However schools seem to think that knowledge of the unit circle (proper) definition is not important, which is bad.
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Avatar for Jassy16
Jassy16
2
Original post by jess2016
I have a mock maths gcse and on my revision list for non calculator I have basic trigonometry and was wondering if you could do it without a calculator as I am struggling to find a formulae that is without a calculator.


from my experience you would need to know what angles represent whole numbers
eg if you have angle 30 you need to know that sine 30 equals 0.5

what i recommend is to draw out the sone,cos and tan graphs and look at the angles that give integers.

Spoiler

Original post by jess2016
I have a mock maths gcse and on my revision list for non calculator I have basic trigonometry and was wondering if you could do it without a calculator as I am struggling to find a formulae that is without a calculator.

I do AQA, and in the paper we just had this year, they gave us the value for sin45 and we had to substitute that in. I don't think you'd be expected to know things such as sin30 = 0.5 and tan45=1, but check your specification just to be sure :smile:
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Avatar for Swimetti
Swimetti
4
if you draw the trig graphs, if you can do that, you will be able to know what the basic sin cos and tan angles are. for example... sin(90) = 1 (and sin-1(1) = 90), sin(30) = 0.5. if you can draw the graphs you can see this and then you could maybe work out the questions on the non calculator paper. i hope that is what you meant. i would google the trig graphs(or you could work them out from your calculator)

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