Question

Find the direction angle of the vector b= <-3, 11>.

74.7450
105.2550
164.7450
149.7420

Answer 1

The given vector is b= -3i +11j

b=<-3, 11>

here, base= 3(not -3) (this gives an angle in first quadrant the same angle will foam in second quadrant from -ve x-axis)and perpendicular= 11

Now,

tan(θ')= perpendicular/base = 11/3

θ' = tan⁻¹(11/3)

= 74.7448°

but we require the angle from positive x-axis so,

θ = 180-θ'

= 180-74.7448

= 105.255°

B is the correct answer.