so i understand part a, but I dont understand how to do part b. please help!(adsbygoogle = window.adsbygoogle || []).push({});

You are given a vector in the xy plane that has a magnitude of 90.0 units and a y component of -40.0 units.

(a) What are the two possibilities for its x component?

I got 80.6 and -80.6.

(b) Assuming the x component is known to be positive, specify the vector which, if you add it to the original one would give a resultant vector that is 90.0 units long and points entirely in the -x direction. What is the magnitude and direction?

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# Need help understanding this problem!

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