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By Socalnick (Socalnick) on Friday, June 04, 2004 - 04:50 pm: Edit |

ok everyone post the hardest IIc question without the answers so other people can see what aeras they need to refresh.

By Mattlord (Mattlord) on Friday, June 04, 2004 - 06:03 pm: Edit |

bring up his post!

By Haruhara (Haruhara) on Friday, June 04, 2004 - 06:14 pm: Edit |

difference between Cos and cos?

permutations/combinations... there are some special ones like circular perms and combs

3-d coordination geometry - distance between a plane (equation here) and some point in space

By Satchamp (Satchamp) on Friday, June 04, 2004 - 06:24 pm: Edit |

The region of the xy plane that satisfies y > x2 or y > 0 is

(A) a circle

(B) a square

(C) the region of the plane bounded by a parabola

(D) a crescent-shaped region in the plane

(E) the half of the plane above the x-axis

By Satchamp (Satchamp) on Friday, June 04, 2004 - 06:25 pm: Edit |

whoa....how do u find the distance between a point and a plane......or a point and a line?

By Scion (Scion) on Friday, June 04, 2004 - 06:48 pm: Edit |

um... point and line (in standard form)... its something like the absolute value of Ax+By+C, divided by the square root of A2+B2. and for a point and a plane, same thing, except for Ax+By+Cz+D. hope that helps.

By Joshjmgs (Joshjmgs) on Friday, June 04, 2004 - 06:50 pm: Edit |

The region of the xy plane that satisfies y > x2 or y > 0 is

I would think it should be where x0 (the whole second quadrant) and the line y>2x

By Socalnick (Socalnick) on Friday, June 04, 2004 - 06:51 pm: Edit |

point and line

x,y= point

A,B,C coefficiants of the line in Ax+Bx+C=0 form

Y,m,b coefficiants of the line in Y=mx+b form

d=abs(Ax+Bx+C)/squrt(A^2+B^2)

d=abs(mx-Yy+b)/squrt(m^2+1)

i did these from memory so you might want to check it for yourseilf

By Socalnick (Socalnick) on Friday, June 04, 2004 - 06:56 pm: Edit |

-statchamp

do u mean y>2x (a line)

or y>x^2 (parabola)

By Satchamp (Satchamp) on Friday, June 04, 2004 - 07:01 pm: Edit |

its y=X^2

umm.....and for sum reason the answer is E ....even though i think it shud be C

oh well......

thx.for the distance formulas........

hey wut bout the formula for distance between a point and a plane? wait i think sum1 wrote it

By Socalnick (Socalnick) on Friday, June 04, 2004 - 07:04 pm: Edit |

distance between point and plane AX+BY+CZ+D=0 form and the point is (x,y,z)

abs(Ax+By+Cz+D)/sqrt(A^2+B^2+C^2)

By Monoe (Monoe) on Friday, June 04, 2004 - 07:04 pm: Edit |

Yes, and y > 2x, y > 0 have redundancy. So the region is simply the positive-y half of the xy plane.

The locus of points equidistant from a line and a point is a parabola - the line is the directrix, the point is the focus.

The locus of points equidistant between a point and a plane is a three-dimensional parabola, if you can imagine it. Sort of an outward-tapering cup. A good analogy would be a vase that keeps opening wider, wider, wider.

By Kewlkiwi102 (Kewlkiwi102) on Friday, June 04, 2004 - 07:05 pm: Edit |

It is E, becuase it says y>x^2 OR y>0.....So, it could be the whole area above the X axis. If they had said AND, then C would be correct.

By Socalnick (Socalnick) on Friday, June 04, 2004 - 07:06 pm: Edit |

its y>x^2 OR y>0

it would be C if it was y>x^2 AND y>0

By Satchamp (Satchamp) on Friday, June 04, 2004 - 07:07 pm: Edit |

oh yeah!!

damn i hope i dont make these silly errors tomorrow......i REALLY REALLY really do!

sigh

By Katiya (Katiya) on Friday, June 04, 2004 - 07:16 pm: Edit |

my life is silly errors.

i am good at math. really. i get all As in honors math classes. but SAT math kills me bc i am always in such a panic or rushing or just plain tired because i don't do well in the morning or whatever. i give the volume instead of the surface area. i do csc instead of sec. i mistype things into my calculator. ARGGGG sats suck.

By Haruhara (Haruhara) on Friday, June 04, 2004 - 07:44 pm: Edit |

distance from point to a line -

first, take the slope of the line. (say it's "u")

secondly, take that slope and get the negative inverse of "u" to get -1 / u (in order to get the slope of a line perpendicular to the original line)

3rd - write a new equation of the new line using the negative inverse of "u" in slope-intercept form

4th- take the coordinates of the point and plug it them into the respective values for the new, perpendicular line

5 - find the y-intercept of the second, perpendicular line.

6 - now equate the y values of the 1st and 2nd lines to get the value of x that they intercept, and find the y coordinate using this x.

7 - based on the new point, use pythagorean theorem to find the distance between these points.

By Satchamp (Satchamp) on Friday, June 04, 2004 - 07:47 pm: Edit |

8. i die doing math......

By Satchamp (Satchamp) on Friday, June 04, 2004 - 07:56 pm: Edit |

yea try this one.....

A coin is tossed 4 times....if it lands on heads more than twice....whats the prob. it lands heads all 4 times?

A. 1/2

b. 1/3

c. 1/4

d. 1/5

e. 1/6

By Student8712 (Student8712) on Friday, June 04, 2004 - 08:16 pm: Edit |

1/2*1/2 so 1/4

By Satchamp (Satchamp) on Friday, June 04, 2004 - 08:29 pm: Edit |

Wrrrrrrrrroong

its 1/5

i cudnt do it either...so ow well.....

WE KNOW IT LANDS MORE THAN TWICE......

MORE THAN twice

not just TWICE

By Student8712 (Student8712) on Friday, June 04, 2004 - 09:03 pm: Edit |

huh? can you explain that one?

By Student8712 (Student8712) on Friday, June 04, 2004 - 09:17 pm: Edit |

Can anyone explain problem 48 in Real SAT IIs (Math IIc of course):

Which of hte following has an element that is less than any other element in that set?

I. The set of positive rational numbers

II. The set of positive rational numbers r such that r^2 is greater than or equal to 2.

III. The set of positive rational numbers r such that r^2 is greater than 4.

A. none

B. I only

C. II only

D. III only

e I and III

The book says the answer is A but i think that might me a mistake. I think the answer is B.

By Satchamp (Satchamp) on Friday, June 04, 2004 - 09:24 pm: Edit |

aite...i hav no idea....i cudnt understand it thats why i asked!

By Shaka (Shaka) on Friday, June 04, 2004 - 09:31 pm: Edit |

I HATE PERMUTATIONS AND COMBINATIONS!!

By Luckystar1111 (Luckystar1111) on Friday, June 04, 2004 - 09:34 pm: Edit |

Student, the answer is not B because when x is greater than zero, it can be .01, .001, .0001, and so on. Since the possibilities are infinite, there is no smallest answer.

By Student8712 (Student8712) on Friday, June 04, 2004 - 09:43 pm: Edit |

Also does anyone get:

If n distinct planes intersect in a line, and another line l instersects one of these planes in a single point, what is the least number of these n planes that l could intersect?

A. n

B. n-1

C. n-2

D. n/2

E. (n-1)/2

The answer is B

By Student8712 (Student8712) on Friday, June 04, 2004 - 09:46 pm: Edit |

deleted

By Eeeeyor (Eeeeyor) on Friday, June 04, 2004 - 11:00 pm: Edit |

can someone explain that probablility questions?

By Optimizerdad (Optimizerdad) on Saturday, June 05, 2004 - 01:34 am: Edit |

Answer to the probability question:

If it lands on heads more than twice, it lands either 3 or 4 times. This is the same as getting exactly 1 or 0 tails.

Required probability = (Prob. of getting 4 heads) / (Prob. of getting 1 or 0 tails)

Prob. of getting 4 heads = (1/2)^4 = 1/16

Prob. of getting 1 tails = (Prob. that 1st coin is tails & rest are heads) + (Prob. that 2nd coin is tails & rest are heads) + ... + (Prob. that 4th coin is tails and rest are heads)

= (1/16) + (1/16) + (1/16) + (1/16) = 1/4

Prob. of getting 0 tails = (1/2)^4 = 1/16

Therefore, required probability = (1/16) divided by ( (1/16) + (1/4))

= (1/16) * (16/5) = 1/5

By Optimizerdad (Optimizerdad) on Saturday, June 05, 2004 - 01:43 am: Edit |

Student8712:

For an answer to the rational numbers problem, see 'Real math sat iic: how to do # 35, 48' posted around 12:00 pm on June 4th, within this thread.

By Optimizerdad (Optimizerdad) on Saturday, June 05, 2004 - 01:58 am: Edit |

Student8712:

...and for the question about planes, see 'SAT II MATH IIC help NEEDED ASAP' from a few days ago, within this thread.

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