v = (7,2,−10), w = (2,6,4) Find the angle θ between the vectors v and w
asked Nov 24, 2016 in Other Math Topics by Elise

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||v||=√(49+4+100)=√153=3√17; ||w||=√(4+36+16)=√56=2√14.

Product of these magnitudes=6√238.

Dot-product v•w=7*2+2*6+(-10)(4)=14+12-40=-14.

cos(theta)=dot-product/(product of magnitudes)=-14/6√238=-0.15125 approx.

Therefore theta = 98.70º approx.
answered Nov 24, 2016 by Rod Top Rated User (487,100 points)
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