97.9°
79.7°
63.4°
36.4°
Correct answer is B
m.n=|m||n|cosθ
(3i+4j).(2i−j)=6−4=2
2=|(3i+4j)||(2i−j)|cosθ
|3i+4j|=√32+42=√25=5
|2i−j|=√22+(−1)2=√5
2=5(√5)(cosθ)
cosθ=25√5=0.08√5
\theta = \cos^{-1} 0.1788 = 79.7°
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