Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2008-12-24 20:34:21

Identity
Member
Registered: 2007-04-18
Posts: 934

exact value

Find the exact value of

Is there a way to do this without drawing a triangle, what's the most efficient way? The book doesn't say which way it should be done.


Also, when finding

using triangles, you could have opp/adj = 2/-1 or opp/adj = -2/1 ... so couldn't there be 2 possible solutions?

Last edited by Identity (2008-12-24 21:29:59)

Offline

#2 2008-12-24 22:16:42

luca-deltodesco
Member
Registered: 2006-05-05
Posts: 1,470

Re: exact value




Trying both roots, the positive is correct, the negative incorrect

...







infact, it turns out that you must take the negative root, if x is negative, and the positive root if x is positive

Last edited by luca-deltodesco (2008-12-24 22:28:06)


The Beginning Of All Things To End.
The End Of All Things To Come.

Offline

#3 2008-12-25 00:03:53

Identity
Member
Registered: 2007-04-18
Posts: 934

Re: exact value

Wow, very nice ! Thanks luca

Offline

#4 2008-12-25 00:25:43

Daniel123
Member
Registered: 2007-05-23
Posts: 663

Re: exact value

I think it's much quicker/easier/nicer to draw a triangle. The identities luca's used all come from triangles anyway.

Offline

#5 2017-07-14 16:11:51

Monox D. I-Fly
Member
From: Indonesia
Registered: 2015-12-02
Posts: 2,000

Re: exact value

Daniel123 wrote:

I think it's much quicker/easier/nicer to draw a triangle. The identities luca's used all come from triangles anyway.

Agree. By looking at the sine value, we know that the height is 4 and the hypotenuse is 5. Thus, with the Pythagorean theorem we know that the base is 3.


Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.

Offline

Board footer

Powered by FluxBB