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Specialist Maths 1/2 Question Thread
Hello !! Does anyone know how to do the question below. I'm pretty sure it has something to do with trig:
1. cos 4A + 1 is equal to:
A 2(cos A – 1)2
B 2 cos2 2A
C cos2 A
D sin 2A
E 1 – sin 2A
- Edited
Using the double angle formula: (http://www.mathguide.com/lessons2/TrigAngles/daf00.gif)
cos(4A) +1
= 2 cos2(2A) - 1 + 1
= 2 cos2(2A)
So B!
5 months later
in the Cambridge textbook ch 3A, Q15...
The Fibonacci sequence is defined by F1 = 1, F2 = 1 and Fn+2 = Fn+1 + Fn for n ∈ N. Use the rule to find F3, F4 and F5. Show that Fn+2 = 2Fn + Fn−1 for all n ∈ N.
How do you do the 'show' part?
lovelyherring In the new equation we have eliminated F(n+1), so try thinking about what could be substituted there.
TnGn74 '
oh lol I see... so basically you can say that F(n+1) = Fn + F(n-1) and then sub that F(n+1) in the old equation so that:
F(n+2) = Fn + F(n-1) +Fn
Then simplify and then:
F(n+2) = 2Fn + F(n-1)
8 days later
Does anyone know where I can find the solutions for chapter 6 in the Cambridge textbook? When I went to go check the answers it says 'see solutions supplement'. Does anyone know what this is referring to?