I keep ending up with the wrong answer on this one.
Line 1 contains the points (-3,7) and (-3,-2). Line 2 contains (0, -4) and (2,6). Find the smallest positive angle from line 1 to line 2.
So I started with finding the equations of the lines:
line 1: x = -3 line 2: y = 5x - 4
Now I was given an identity that says the slopes of the lines are the tangents of the angles between the line and x-axis.
So on the first line I can't get the tangent, but I know the angle is 90 degrees. On the second the tangest is 5, so taking the inverse of that I got 78.69.
I then subtracted that from 90 and got 11.31 degrees. But I was told the answer is 168.7. Where did I go wrong?
Ok, the angle that line 1 makes with line two is negative for the acute angles because starting from one and going to two is a clockwise rotation in those parts. That makes sense. Thanks.
Interactive Math Goodies Software
Topic Locked
Posted - 09/26/2007 : 23:41:48
