Răspunsuri

2014-04-11T21:21:41+03:00
u * v = |u| * |v| * cos a = 7 * 8 * cos 45 = 5*8*radical din 2/ 2 = 20 * radical din 2
1 1 1
2014-04-11T21:27:22+03:00
U * v = |v| * |u| * cos 15 grade
cos 15 = cos(45-30)=cos45cos30+sin45sin30=radical 2/2 * radical din 3/2 + 1/2 * radical din 3/2 = √6 + √2 totul supra 4
u * v = 7 * 8 * (√6+√2)/4 = 14 * (√6+√2)
1 1 1