<p>I thought it was cos(4x+...)??? Was there some trick to that question? I remember it being in the beginning of the test, so I didn't think too much about it.</p>
<p>P=2PI/B was what I tried to relate it to. I forgot the original equation. I think it was sin(2PIt) or something?</p>
<p>" if a line intersects a plane perpindicularly, what is the set of points that are 4 units from the line and 5 units from the plane"</p>
<p>this was 2 circles or 4 points?</p>
<p>Heartbeat was 120</p>
<p>The Period one was (A) I believe, the one with 4x (period is 360 / 'coefficient of x'), in that case the coefficient of 'x' was 2, and only choice A had a diff. coefficient (4x)</p>
<p>i think the original function had cos(2x + something), so the period is 2pi/2 = pi</p>
<p>looking at the choices, they were all cos or sin with the x having a coefficient of 2 except for the cos(4x ...) choice</p>
<p>can you PLEASE
explain the heartbeat problem</p>
<p>Wait, so answers to these:</p>
<p>1) Different period question's answer was cos(4x+...) right?
2) I got 2 circles for the perpendicular intersect.</p>
<p>or if the right answer wasn't cos (i wasn't paying attention) then it was sin 4x</p>
<p>line perpendicular to plane => line goes through plane => 4 units about line makes a circle 5 units above the plane and five units below the plane</p>
<p>LZfan, the 4x one was choice (C) I think. Not A... or am I just not remembering correctly? but it WAS cos(4x+...) right???</p>
<p>sky2345, if you can remember the exact question, post it and I'll explain to you because I, for the life of me, cannot remember how the question went, but what I do remember is that the answer was 120.</p>
<p>aquamarinee, diff. period was cos (4x...) that's correct. The second one, I personally chose 2 points because none of the other answers seemed correct and I don't think it'll affect my score so I'm not entirely sure of that one.</p>
<p>It DEFINITELY was cos (4x....) whether answer choice A or C it doesn't matter but yes it WAS 4x</p>
<p>Cool. Thanks LZfan. </p>
<p>I chose 2 circles because all the points +-4 and +-5 would create 2 inclusive circles. It's not just those 4 points that will be in the set.</p>
<p>The thing that confused me was that it said it was a "line" and not a "line segment". I still haven't figured it out yet, I'm trying to imagine HOW the two circles choice would be correct but no luck yet. Anyhow, it's just this question I'm unsure of, and I left out the pet's dish questions because I ran out of time, so overall I'm satisfied.</p>
<p>Anyone else get an answer for the perpendicular lines one? I was pretty sure on that one, but now I'm not as sure...</p>
<p>if the two circles were parallel to the plane on opposite sides it makes sense....but i hope it doesnt since i put 4 points</p>
<p>i put 2 circles
the radius would be 4 so each point on the circle would be 4 units away from the line and 5 units away from the intersection point.
and was it line? or line segment? anybody remember?</p>
<p>elec486, that is true. but it also applies to the 4 points... who knows where any of the options they gave where located! oh the ambiguities of collegeboard......</p>
<p>I said 4 points... if you think visually, in terms of a horizontal plane and a line cutting through it vertically, then there really are only 4 points where it would be 5 points above/below the plane AND 4 points to the left/right of the line.</p>
<p>...Right?</p>
<p>Aquamarinee, I don't think this will help you, but I got 120 on the heartbeat question by just plugging in f(t) = 60 (sec), so you would just plug 60 into the sin(2pit) -> sin(2pi60). It was all calculator.</p>
<p>I think they meant a line from A to B... so a line segment would make sense... Or was that a different question?</p>
<p>YES! Plugging in, that's how I did it, the heartbeat question. It really was that simple. And it was definitely a LINE not a segment.</p>
<p>The heartbeat one was question #44 or something, so I didn't think that you were supposed to just plug in the 60... Hmm... I don't even know if I answered that one or not, since I wasn't 100% sure. Hahaha. I thought it might have been 60, but I don't think I put anything down. That was one of the 6 I skipped probably...</p>
<p>For the perp. line question, I thought that they had something in there that meant that not just those 4 points would be included, but all points that would be enclosed in the circle would have been valid.</p>