# C3 trig questionsWatch

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#1
Hi I am very bad at trigonometry and I don’t understand questions 9d to 9g

Please could someone explain how do do these?

Thanks
0
3 weeks ago
#2
sin2Θ can be written as 2sinΘcosΘ

similarly sinΘ can be written as 2sin(Θ/2)cos(Θ/2)
0
3 weeks ago
#3
For the other questions, for:
e) Try the R-fomulas,
f) Try the sum-product formula,
0
#4
(Original post by simon0)
For the other questions, for:
e) Try the R-fomulas,
f) Try the sum-product formula,
thank you , i am just struggling on 9f still, i dont know how to do that , thanks
0
#5
(Original post by the bear)
sin2Θ can be written as 2sinΘcosΘ

similarly sinΘ can be written as 2sin(Θ/2)cos(Θ/2)
thank you
0
3 weeks ago
#6
for f) you can use one of these formulae:

0
3 weeks ago
#7
How did it go?
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#8
(Original post by the bear)
for f) you can use one of these formulae:

I don’t think I have learnt it before I will check it up at school , thanks
0
3 weeks ago
#9
Is this A-Level ? , becauase this level of trigonemetry definitely isn't on Edexcel Mathematics and I'm in top set amd have never seen it.
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3 weeks ago
#10
(Original post by Kane M. Gordon)
Is this A-Level ? , becauase this level of trigonemetry definitely isn't on Edexcel Mathematics and I'm in top set amd have never seen it.
Yeah some of the questions they put in the textbook are much weirder and harder compared to questions
on actual papers.
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3 weeks ago
#11
(Original post by Ken Poison)
I don’t think I have learnt it before I will check it up at school , thanks
They are in the formula booklet (at least for Edexcel) however, they can also be derived.

We know:

Then just subtract the terms:

Last edited by simon0; 3 weeks ago
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