<p>I've been trying to figure out how to do p. 860 (18) + p. 807 (15). They're both diagrams. Thanks in advance!</p>
<p>for number 18 on pg 860 it is a ratio problem.</p>
<p>if you look at the point shown you can draw another triangle parallel with the axis with an x of 4 and a y of 10. </p>
<p>From this you can infer that c=2root(29)</p>
<p>set up your new ratio as 4/x, 10/y, 2root(29)/c Then plug and chug with the answers that are given. Choice A gives a ration of 2:1 for each value making it a possible answer. 4/2 =2 10/2 =5 2root(29)/2 = root(29)</p>
<p>For number 15 on page 807 it is more of a logic problem(at least imo).</p>
<p>Even though it may not look like it, each triangle is a right triangle. So, we can make some assumptions about the angles based on our knowledge of 90 degree triangles. The longer the length of our hpypotinuse the smaller the measure of the angle at the bottom of the triangle. XD is the longest hypotinuse, therefore making angle XDY the smallest angle in question.</p>
<p>I'm sure there is a mathematical way to figure this out, but logic is the quickest for me.</p>
<p>Thanks, icebarracuda, I would have never thought to draw another triangle. - -;</p>
<p>And I understand the cube problem now, your explanations were very clear. Thank you so much. =]</p>
<p>[ul]
[li]860 / 18 /[/li][/ul]
slope = rise/run</p>
<p>For the line passing through (0,0) and (4,10)
slope = 10/4 = 5/2.</p>
<p>The same line goes through A and B, so
slope = BC/AC = 5/2.</p>
<p>(A) is the answer.</p>
<p>can someone explain how you can tell the other angle just based on the hyp for question 15, pg 807</p>
<p>can someone explain how you can tell the other angle just based on the hyp for question 15, pg 807</p>
<p>
</p>
<p>For this problem, you should understand the relationship of a triangle's sides to its angles. As a triangle's side gets bigger, the angle opposite that side gets bigger as well. As the base of the triangles lies along the bottom face of the cube, it will be longest at the diagonal of the cube. Since angle Y is always a fixed 90 degrees (look closely at the diagram if you don't realize this), you know the angles that must be changing are X and D. Since X is opposite the side getting larger, it is growing when the base of the triangles grow; therefore angle D reaches its minimum measure when X reaches its maximum X, and X reaches its maximum measure when the side opposite it is longest, which is when that side is the diagonal of the cube. That's why angle XDY is the answer.</p>
<p>So question 18 on page 860 is all about the slope thing?</p>