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An ant crawls on the sidewalk. It first moves south a distance of 10 cm. It then turns southwest and crawls 6 cm. What is the magnitude of the ant’s displacement?

User LayfieldK
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1 Answer

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Step-by-step explanation:

the displacement is the length of direct line of sight from the starting point to the end point. in other word the baseline of the created triangle.

the legs of that triangle are 10 cm and 6 cm.

the angle between both legs is 90 + 45 = 135°.

because 90° is the angle between South and West. and for southwest we have to add 45°

the law of cosine :

c² = a² + b² - 2ab×cos(C)

c is a side, C is the opposite angle, a and b are the other 2 sides.

so, we have in our case

displacement² = 10² + 6² - 2×10×6×cos(135) =

= 100 + 36 - 120×cos(135) =

= 136 - 120×-0.707106781... =

= 136 - 120×-sqrt(2)/2 =

= 136 + 60×sqrt(2) =

= 220.8528137...

displacement = 14.86111751... cm ≈ 15 cm

User Amy Groshek
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