proving trig identities: csc^4 - cot^4 = csc^2 + cot^2

891006

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Oct 8, 2007
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I need help with one or both:

1) csc^4 - cot^4 = csc^2 + cot^2

2) (1 - tan^2) / (1 + tan^2) = 1 - 2sin^2

Thanks!!
 
Re: proving trig identities

891006 said:
i need help with one or both:

csc^4 - cot^4 = csc^2 + cot^2

Hints:

Use

a^2 - b^2 = (a+b)(a-b)

and

1 + cot^2(x) = cosec^2(x)



(1 - tan^2) / (1 + tan^2) = 1 - 2sin^2

Hints:

1 + tan^2(x) = sec^2(x)


Thanks!!
 
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