What is the angle between #<6 , 5 , 7 > # and # < 3 , 3 , 2 > #?

1 Answer
Feb 12, 2017

The angle is #=17.2#º

Explanation:

The angle between #vecA# and #vecB# is given by the dot product definition.

#vecA.vecB=∥vecA∥*∥vecB∥costheta#

Where #theta# is the angle between #vecA# and #vecB#

The dot product is

#vecA.vecB=〈6,5,7〉.〈3,3,2〉=18+15+14=47#

The modulus of #vecA#= #∥〈6,5,7〉∥=sqrt(36+25+49)=sqrt110#

The modulus of #vecB#= #∥〈3,3,2〉∥=sqrt(9+9+4)=sqrt22#

So,

#costheta=(vecA.vecB)/(∥vecA∥*∥vecB∥)=47/(sqrt110*sqrt22)=0.96#

#theta=17.2#º