Original post by Sokka
hey! 
ok, so the last part of the question I got:
(3cosx-1)(cosx+3) when I factorised.
I then got cosx=1/3
However, the stupid mark scheme says it is: cos2x=1/3, and then it shows the steps taken to solve cos2x=1/3
I thought it was cosx=1/3, not cos2x=1/3 - I mean where the hell does the cos2x come from? It is clearly cosx=1/3 from the factorisation right? Any ideas how to not make this mistake in the exam? I have no idea where the 2x comes from, plz help :]
ok, so the last part of the question I got:(3cosx-1)(cosx+3) when I factorised.
I then got cosx=1/3
However, the stupid mark scheme says it is: cos2x=1/3, and then it shows the steps taken to solve cos2x=1/3
I thought it was cosx=1/3, not cos2x=1/3 - I mean where the hell does the cos2x come from? It is clearly cosx=1/3 from the factorisation right? Any ideas how to not make this mistake in the exam? I have no idea where the 2x comes from, plz help :]
Lol your using subst theta = 2x, so it is 2x clearly its not x but clearly its 2x, can u see how obviosuly its 2x and not x because theta = 2x and not x so clearly its 2x do you understand?
ok, il use % as a sign for theta, last part of question it says solve the equation 3tan2x = 8/sin2x,
u worked out 3tan% = 8/sin% can be wrriten as 3cos%^2 +8cos% - 3 = 0 from first part
there fore by subst % = 2x u get 3cos2x^2+8cos2x-3=0
factorising gives (3cos2x-1)(cos2x+3)
just remember ur subst % for 2x
u worked out 3tan% = 8/sin% can be wrriten as 3cos%^2 +8cos% - 3 = 0 from first part
there fore by subst % = 2x u get 3cos2x^2+8cos2x-3=0
factorising gives (3cos2x-1)(cos2x+3)
just remember ur subst % for 2x
Original post by Sokka
hey! ok, so the last part of the question I got:
(3cosx-1)(cosx+3) when I factorised.
I then got cosx=1/3
However, the stupid mark scheme says it is: cos2x=1/3, and then it shows the steps taken to solve cos2x=1/3
I thought it was cosx=1/3, not cos2x=1/3 - I mean where the hell does the cos2x come from? It is clearly cosx=1/3 from the factorisation right? Any ideas how to not make this mistake in the exam? I have no idea where the 2x comes from, plz help :]
ok, so the last part of the question I got:(3cosx-1)(cosx+3) when I factorised.
I then got cosx=1/3
However, the stupid mark scheme says it is: cos2x=1/3, and then it shows the steps taken to solve cos2x=1/3
I thought it was cosx=1/3, not cos2x=1/3 - I mean where the hell does the cos2x come from? It is clearly cosx=1/3 from the factorisation right? Any ideas how to not make this mistake in the exam? I have no idea where the 2x comes from, plz help :]
Look at the question
how is 3tan% = 8/sin% similar to....
3tan2x = 8/sin2x
they've subbd in 2x instead of %, ask ya teacher before the exam if your still struggling, no other way of explaining
Original post by Sokka
oh im such as idiot for gods sake! I didnt even read the equation in the last part of the question therefore I didn't see that they substituted 2x for theta (%). Why am I an idiot, why oh whyyyyy! im ready to fail this exam ...
thanks for the help mate
thanks for the help mate
no problem, best of luck
Quick Reply
Related discussions
- Help trig
- Trigonometry alevel maths q
- Trigonometry equations
- Mistake in the maths solution bank?
- Trig Exam Question
- What topics are NOT in the non calculator paper in GCSE maths?
- Maths trig problem
- Factorising quadratics when a isn't 1
- circle question help
- Help trig
- SMC Tips and Tricks
- How to solve is trigonometric differentiation problem?
- AS-level Edexcel Pure Paper 2023, 18th May
- maths
- isaac physics Lorentz Transform 1
- Integration question
- Highers
- pure 3 trig is killing me
- AQA Level 2 Further Maths
- Level 2 Further Maths - Post some hard questions (Includes unofficial practice paper)
Latest
Trending
Last reply 2 days ago
Did Cambridge maths students find maths and further maths a level very easy?Last reply 2 weeks ago
Edexcel A Level Mathematics Paper 2 unofficial mark scheme correct me if wrongMaths
71
Trending
Last reply 2 days ago
Did Cambridge maths students find maths and further maths a level very easy?Last reply 2 weeks ago
Edexcel A Level Mathematics Paper 2 unofficial mark scheme correct me if wrongMaths
71
