Let u have a length of 20 and direction of 60 degrees, and v= 5i-3j

Question

what is u?

what is abs(2v-u)?

Answer 1

let u = [a,b]
then a^2 + b^2 = 20 and tan60° = b/a = √3
b = √3 a
back in a^2 + b^2 = 20
a^2 + (√3a)^2 = 20
a^2 + 3a^2 = 20
a^2 = 5
a = ±√5
b = ±√15

u = [√5,√15] or [-√5,-√15] or in your notation
u = ±√5i ± √15

then 2v - u = (10-√5)i + (√15-3)j
abs(2v-u) = √(100 - 20√5 + 5 + 15 - 6√15 + 9)
= etc

repeat for the other value of u

Answer 2

solve the rest because i am not getting correct answer?

Answer 3

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