Trig Indentity problem

chiurox

New member
Joined
Aug 14, 2007
Messages
10
Hi, I was wondering how to solve this:
If we establish an identity, 4sec2A - 7tan2A would equal what?
 
chiurox said:
I came across another problem:
(tanA - cotA) / (tanA + cotA)

so far for this one, I got:
sin²A - cos²A .... but is there any way I can further simplify this?
 
chiurox said:
chiurox said:
I came across another problem:
(tanA - cotA) / (tanA + cotA)

so far for this one, I got:
sin²A - cos²A .... but is there any way I can further simplify this?

ok, I used the sin²A + cos²A = 1 to substitute for the (-cos²A)

Can anyone check if the answer is -1 ??

PS: I'm still having some problems with the first question. =(
 
chiurox said:
chiurox said:
chiurox said:
I came across another problem:
(tanA - cotA) / (tanA + cotA)

so far for this one, I got:
sin²A - cos²A = - cos(2A)


.... but is there any way I can further simplify this?

ok, I used the sin²A + cos²A = 1 to substitute for the (-cos²A)

Can anyone check if the answer is -1 ?? ..... NO
PS: I'm still having some problems with the first question. =(
 
chiurox said:
Hi, I was wondering how to solve this:
If we establish an identity, 4sec2A - 7tan2A would equal what?

Are you saying:

4sec(2A) - 7tan(2A)

or

4sec^2(A) - 7tan^2(A) .....^2 means squared
 
Subhotosh Khan said:
chiurox said:
Hi, I was wondering how to solve this:
If we establish an identity, 4sec2A - 7tan2A would equal what?

Are you saying:

4sec(2A) - 7tan(2A)

or

4sec^2(A) - 7tan^2(A) .....^2 means squared

it's 4sec^2(A) - 7tan^2(A) sorry, I remember I typed it right...

oh, about that other question: how did you get from sin^2A - cos^A = cos2A ?
 
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