Question #8f4d7

1 Answer
Sep 13, 2016

55.8^@55.8, rounded to one decimal place.

Explanation:

Given two vectors
vecSS, with |vecS|=4S=4 and vecRR, with |vecR|=6R=6
Let thetaθ be the angle between the two.
By definition of dot product we have
vecS cdot vecR=|vecS||vecR|cos thetaSR=SRcosθ
Equating to the given value we get
|vecS||vecR|cos theta=13.5SRcosθ=13.5
=>4xx6cos theta=13.54×6cosθ=13.5
=>cos theta=13.5/24=0.5625cosθ=13.524=0.5625
=> theta=cos^-1 0.5625θ=cos10.5625
=> theta=55.8^@θ=55.8, rounded to one decimal place.