Math Is Fun Forum

niharika_kumar

Member

From: Numeraland

Registered: 2013-02-12

Posts: 1,062

trigonometry#4

If

,
then prove that

It seems easy but I don't know why am I not able to solve it.

Pls help.....

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friendship is tan 90°.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: trigonometry#4

hi Niharika,

So I thought: replace every cos^2 with 1 - sin^2 and simplify. (I've left out some simplification steps ... you'll have to put them in yourself.)

Now to use the given equation:

Use this to simplify E by removing the highest power:

Go back to the given equation and use it again to remove the 4th power term:

therefore

QED.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

niharika_kumar

Member

From: Numeraland

Registered: 2013-02-12

Posts: 1,062

Re: trigonometry#4

wow

thanks.

---

friendship is tan 90°.