1. ## dist question..

$L_2(-\pi,\pi)\\$
$W=Sp(1,\cos 2t)\\$
find
$dist (\cos^2t,w)$

did i solved it correctly:
http://i33.tinypic.com/2uqoy9u.jpg

2. If you are meaning to find the distance of $\cos^2t$ to the span of $\{1,\cos 2t\}$, just observe that the distance is 0 because $\cos^2t$ belongs to this span since $\cos^2t=(1/2)1+(1/2)\cos2t$