SOLUTION: Find the angle between the two vectors in -9i+ 8j, 10i- 8j

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Question 1103870: Find the angle between the two vectors in -9i+ 8j, 10i- 8j
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use the dot product.
u%2Av=abs%28u%29abs%28v%29cos%28theta%29
abs%28u%29=sqrt%28%28-9%29%5E2%2B8%5E2%29=sqrt%2881%2B64%29=sqrt%28145%29
abs%28v%29=sqrt%2810%5E2%2B%28-8%29%5E2%29=sqrt%28100%2B64%29=sqrt%28164%29
u%2Av=-9%2810%29%2B%288%29%28-8%29=-90-64=-154
So,
cos%28theta%29=%28-154%29%2Fsqrt%28145%2A164%29
cos%28theta%29=-154%2Fsqrt%2823780%29
cos%28theta%29=-0.99865
theta=177.03