2011 hsc mx1 marathon (2 Viewers)

bleakarcher

Active Member
Joined
Jul 8, 2011
Messages
1,509
Gender
Male
HSC
2013
note: questions may only be posted by the solver of the previous problem
to start off:
d/dx[cos^(-1)[-1/x]]
 

evanstroeve

Premium Member
Joined
Oct 16, 2009
Messages
100
Gender
Male
HSC
2011
Using chain rule,



Let each arrangement of the letters D E L E T E D be a word.
How many words are there where the D's are separated?
 

apollo1

Banned
Joined
Sep 19, 2011
Messages
938
Gender
Male
HSC
2011
300

ill post question when someone confirms or denies my answer
 
Last edited:

apollo1

Banned
Joined
Sep 19, 2011
Messages
938
Gender
Male
HSC
2011
ok heres another question

Akram estimates that the probability of his winning any one game of tennis against a particular opponent is 1/3. How many games should they play so that the probability that akram wins at least one game is greater than 0.9 .
 

artosis

Member
Joined
Apr 15, 2011
Messages
149
Gender
Male
HSC
2011
<a href="http://www.codecogs.com/eqnedit.php?latex=LHS = (1-sin^2x)^2 @plus;sin^2x \\= 1 - 2sin^2x @plus; sin^4x @plus; sin^2x \\ = sin^2x@plus;cos^2x-2sin^2x@plus;sin^4x@plus;sin^2x \\ = cos^2x @plus;sin^4x \\ =RHS" target="_blank"><img src="http://latex.codecogs.com/gif.latex?LHS = (1-sin^2x)^2 +sin^2x \\= 1 - 2sin^2x + sin^4x + sin^2x \\ = sin^2x+cos^2x-2sin^2x+sin^4x+sin^2x \\ = cos^2x +sin^4x \\ =RHS" title="LHS = (1-sin^2x)^2 +sin^2x \\= 1 - 2sin^2x + sin^4x + sin^2x \\ = sin^2x+cos^2x-2sin^2x+sin^4x+sin^2x \\ = cos^2x +sin^4x \\ =RHS" /></a>
 

blackops23

Member
Joined
Dec 15, 2010
Messages
428
Gender
Male
HSC
2011
shit forgot question

cos ALPHA = 1-t^2 / 1 + t^2

3/4 = 1-t^2 / 1+t^2

3 + 3t^2 = 4 - 4t^2

7t^2 = 1

t = +/- 1/(sqrt 7) but as ALPHA IS ACUTE t>0 therefore t = 1/sqrt(7) --> tan (alpha/2) = 1/(sqrt(7))]

EDIT: would i get full marks for this solution in an exam?
 
Last edited:

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top