posted by Anonymous .
A is the point (1,1), B is (4,5) and C is (5,3). Find
a)the angle between AB and a line parallel to the y axis.
b)the angle between BC and a line parallel to the y axis.
c)Hence, find ABC (angle B).
I have drawn the points. Please help!!!
a) In going from A to B, y increases by 4 while x increases by 3. The tangent of angle that the line makes with the y axis is 3/4. That makes the angle 36.87 degrees
b) In going from B to C, y decreases by 2 while x increases by 1. The line points downward and makes an angle tan^-1 1/2 = 26.56 degrees with the -y axis, or 153.43 with the +y axis. The angle at B is the supplement of 153.43 - 26.56 = 126.87, or 53.12 degrees.
You need to work with the figure to followe these steps, and I can't draw the figure for you. It might be easiest to get the angle A by computing the direction of AC first.