Find the unit vector in the direction opposite to the resultant of forces. F\(_1\) = (-2i - 3j) and F\(_2\) = (5i - j)

  • A \(\frac{1}{5}\)(-3i - 4j)
  • B \(\frac{1}{5}\)(-3i + 4j)
  • C \(\frac{1}{5}\)(3i - 4j)
  • D \(\frac{1}{5}\)(3i + 4j)
waec 2020furthermathematics

The correct answer is C. \(\frac{1}{5}\)(3i - 4j)

Resultant 

(- 2i - 3j) + (5i - j)

= 3i - 4j 

Unit vector 

= \(\frac{3i - 4j}{|3i - 4j|} = \frac{3i - 4j}{\sqrt{3i } + (-4)}\)

= \(\frac{3i - 4j}{\sqrt{25}}\) 

= \(\frac{3i - 4j}{5}\)

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