u(8,-3), v(-3,-8).
Tan A = (-8-(-3))/(-3-8) = -5/-11 = 0.45455, A = 24.4o. S. of W.
Find the angle between u=(8,-3) and V=(-3,-8). Round to the nearest tenth of a degree
3 answers
u.v = -24+24 = 0
so u and v are perpendicular
Where did Henry go wrong? 5/11 is the slope of the line between the two points. It is not the tangent of the angle between the two vectors. For that, you need
tanθ = tan(arctan(-8/-3)-arctan(-3/8)) = tan(pi/2)
θ = pi/2
Also note that the two slopes are negative reciprocals:
-3/8 * 8/3 = -1
so u and v are perpendicular
Where did Henry go wrong? 5/11 is the slope of the line between the two points. It is not the tangent of the angle between the two vectors. For that, you need
tanθ = tan(arctan(-8/-3)-arctan(-3/8)) = tan(pi/2)
θ = pi/2
Also note that the two slopes are negative reciprocals:
-3/8 * 8/3 = -1
It's 45 degrees
2 answers