Jawabanmu

2013-12-14T15:13:53+07:00
A.b = 2.(-1) + 1.2 + 3.2 = |a||b|costeta
-2 + 2 + 6 = 3 \sqrt{14} costeta
costeta =  \frac{6}{3 \sqrt{14} }
costeta =  \frac{2}{\sqrt{14} }
costeta= samping/miring jadi 
sisi samping = 2
sisi miring =  \sqrt{14}
dengan phytagoras di dapatkan 
sisi depan =  \sqrt{10}

sin teta = depan/miring
sin teta = \frac{\sqrt{10}}{\sqrt{14}} = \frac{\sqrt{5}}{\sqrt{7}} =  \frac{1}{7}\sqrt{5}