Master Proofs with Ease: Solving Tricky Trigonometric Equations

Thread starter yvette25
Start date Nov 12, 2007
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Proofs

AI Thread Summary

To prove the equations sin3x = sinx (3-4sin^2x), tanx + sinx/2tanx = cos^2(x/2), and cot2x = (cot^2 x-1)/(2cotx), it's suggested to rewrite sin3x as sin(2x+x) for easier manipulation. Simplifying the second and third equations using only sine and cosine functions is recommended. For the last equation, it's important to recall that cot(x) is the reciprocal of tan(x). These strategies aim to facilitate the proof process for each trigonometric equation. Mastering these techniques can significantly enhance understanding of trigonometric identities.

Nov 12, 2007

yvette25

Homework Statement

prove:
sin3x = sinx (3-4sin^2x)

tanx+sinx/2tanx = cos^2(x/2)

cot2x = (cot^2 x-1)/(2cotx)

Last edited: Nov 12, 2007

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Nov 12, 2007

rock.freak667

Homework Helper

...where is your attempt?
But anyhow...for the first one...rewrite sin3x as sin(2x+x)

and well for the second and third ones..try simplifying it into sin and cos only , for the last one...remember that cot(x)=1/tan(x)

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