tricky math questions

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1

<p>[URL=<a href="http://img697.imageshack.us/i/satmath.png/%5D%5BIMG%5Dhttp://img697.imageshack.us/img697/5249/satmath.png%5B/IMG%5D%5B/URL"&gt;http://img697.imageshack.us/i/satmath.png/]

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<p>The triangle is isosceles and AB>AC. Which of the following must be FALSE?
A) AB=BC
B) BC=AC
C) x=y
D) x=z
E) y=z</p>

<p>Ans:E</p>

<p>I really don't get this question. How can choice e be false if a and b are not false as well? I'm thinking that AB= BC, thus x=z.</p>

<p>A positive integer is said to be tri-factorable if it is the product of 3 consecutive integers. How many positive integers less than 1000 are tri-factorable?
Ans: 9</p>

<p>My ans is 8- 6, 24, 120, 210, 326, 504, 720, 990. Is this because 0 is included?</p>

2

<p>Don’t look at the answers as if they are all connected.
y does not equal z because AB is not the same length as AC. For triangles, the longest side corresponds to the biggest angle in the triangle. So since AB (angle z) is less than AC (angle y), then z cannot be equal to y. Besides, if AB=BC, and BC=AC, then wouldn’t AB=AC when it clearly says that AB > AC?</p>

<p>3x4x5=60</p>

3

<p>thanks for your reply!
regarding 1, I understand your explanation about how z cannot be y because AB >AC. but what really bugs me about the question is that the triangle is an isosceles triangle. so this is what it looks like in my head:
[URL=<a href=“http://img718.imageshack.us/i/satmath1.png/][IMG]http://img718.imageshack.us/img718/458/satmath1.png[/IMG][/URL”>ImageShack - Best place for all of your image hosting and image sharing needs]

http://img718.imageshack.us/img718/458/satmath1.png

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<p>If it is an isosceles triangle, and AB> AC, then musn’t AB=BC?</p>

4

<p>If it is an isosceles triangle, and AB> AC, then musn’t AB=BC?</p>

<p>No AB doesnt have to equal BC, because AC could =BC</p>

5

<p>The triangle is isosceles and AB>AC. Which of the following must be FALSE?
A) AB=BC
B) BC=AC
C) x=y
D) x=z
E) y=z</p>

<p>Well, we know that that if it is an isosceles triangle and AB>AC, then either AB=BC or BC=AC, so we can automatically rule out choices A and B.</p>

<p>Furthermore, the Base Angles Theorem tells us that if AB=BC then x=z, and if AC=BC, then x=y. This lets us eliminate choices C and D, and we are left with choice E.</p>

<h1>2</h1>

<p>1<em>2</em>3 = 6
2<em>3</em>4 = 24
3<em>4</em>5 = 60
4<em>5</em>6 = 120
5<em>6</em>7 = 210
6<em>7</em>8 = 336
7<em>8</em>9 = 504
8<em>9</em>10 = 720
9<em>10</em>11 = 990</p>

<p>As gravekitty noted, you skipped 3<em>4</em>5. Zero is not a positive integer, it is neutral, so you are correct by not including it.</p>

6

<p>The rule goes: “In every triangle, the longer side is opposite the larger angle and the shorter side is opposite the smaller angle.”</p>

<p>In other words, since AB>AC z MUST be greater than y.</p>

<p>BC can equal either AB or AC.</p>

7

<p>I have a question to add to the triangle forum. Is the rule that two sides of a triangle, when added together, must always be greater than the third side?</p>

8

<p>Correct, triangle inequality.</p>

9

<p>Someone on the forum needs to make a list of the Math Rules we need to know for the SAT.</p>

10

<p>What if they’re equal? Does this mean it can’t be a triangle?</p>

11

<p>Correct. It’s not a triangle.</p>

12

<p>“Someone on the forum needs to make a list of the Math Rules we need to know for the SAT.”</p>

<p>Or, alternatively, you can listen more at school. I’m pretty sure these laws are in every geometry textbook.</p>