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

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## #1 Re: Help Me ! » line intersection » 2009-03-23 12:36:12

the best tutorials i've ever read about finding the intersections of vectors is here  http://www.tonypa.pri.ee/vectors/start.html . Also, these were written with the idea of coding vectors and collisions in games. enjoy

## #2 Re: Help Me ! » Trigonmetry question cos 15 » 2009-03-15 22:27:29

as fairfax said, change 15pi/2 to 3pi/2 -->then take cos(3pi/2)= 0

## #3 Re: Help Me ! » List of quadrilateral vector proofs » 2009-02-28 05:48:54

regarding

Rhombus:
 Diagonals are perpendicular
 Opposite sides congruent

Diagonals are perpendicular, in and of itself, does not necessarily prove that a quadrilateral is a rhombus; it could also be a kite(not even a parallelogram)
if  Diagonals are perpendicular  and  Opposite sides congruent then you a rhombus you have!

## #4 Re: Guestbook » vote for your fav subjects » 2009-02-26 13:44:38

hmm...i'd go for computer science!

## #5 Re: Guestbook » Mind if I link to your site? » 2009-02-26 13:42:04

i also like this site--i included it in my online educational directory under math teacher resources...keep up the good work here!

## #6 Re: Guestbook » Don't Post here! » 2009-02-26 13:40:12

cool site...my favorite page on the site is http://www.mathsisfun.com/geometry/symmetry-point.html !

hey back!