Jawabanmu

2014-05-22T23:23:38+07:00
Cos α =   a . b
              IaI.IbI
   1/3  = 32 - 16 + m
              (√81)(√(32+m²)
1/3(9√(32+m²) = 16 + m
(3√(32+m²))²²  = (16 + m)²
9(32+m²) = 256 + 32m + m²
9m² - m² - 32m + 288 - 256 = 0
8m² - 32m + 32 = 0
m² - 4m + 4 = 0
(m - 2)² = 0
m - 2 = 0
m = 2