00:02
So for part a, we have cosine is equal to r divided by z.
00:08
And we know r is equal to z cosine.
00:15
So at 80 hertz, r equals 15 times cosine of negative 71 degrees.
00:26
And that gives you 4 .88 at 160 hertz, r equals 13, 10.
00:36
Times cosine of 67, and that gives you 5 .08.
00:44
So the average would be 4 .88 plus 5 .08, divided by 2 gives you 5 .0.
00:59
For part b, we use tangent that's equal to wl minus 1 over wc divided by r.
01:14
R is 5 .0 from part a.
01:17
So at 80 hertz, tangent of negative 71 degrees gives you 2 pi 80 hertz times l minus 1 over 2 pi times 80 divided by 5 .0...