Mathematics - 5 November 2007

Prove this identities:
1.sin(a+30)-sin(a-30)=cos a
2.cos(45+a)+cos(135+a)=-sqrt2*sin a

2007-11-05 09:07:08 · 2 answers · asked by Amir B 1

1
_______
3 - 2^(1/2)

Rationalize the denominator (sorry i dont know how to type square roots on the computer)...

The book's answer is :

1+2^(1/2).
________
7
I dont understand how they got 7 for the denominator. I understand how the numerator came about. I got -6 for the denominator.... please help..

2007-11-05 09:06:08 · 3 answers · asked by gummi 1

thxs

2007-11-05 09:05:37 · 11 answers · asked by ivan_c 2

2007-11-05 09:04:06 · 3 answers · asked by Adam P 1

2007-11-05 09:01:25 · 3 answers · asked by Adam P 1

use a linear approximation to estimate the value of (41/10)^1/2

2007-11-05 09:01:22 · 1 answers · asked by orlandosgrl89 1

find a ten digit number containing each digit once, so the number formed by the first n digitd is divisible by n for each value of n between one and 10.

2007-11-05 08:44:33 · 2 answers · asked by Jason N 2

I Need Help For A Maths Prelim .. Aaagghh

Can SomeOne Get Back To Me Soon Please =)

Thanks.Ox

2007-11-05 08:42:48 · 8 answers · asked by EmmaBabey.Ox 1

change 4 2/3 to an improper fraction worth best awnser for the right anwser

2007-11-05 08:42:33 · 14 answers · asked by jcblackgamer 2

Ok well, we now in math are dividing decimals and they really confuse me. One of the problems is.. Write the smallest power of 10 that you would multiply by to make the number a whole number. The numbers they give u are 7. 9.3, 8. 0.12, 9. 3.05, and 10. 12.001 Help!:)

2007-11-05 08:37:39 · 2 answers · asked by peyton6696 1

Tangent to both axes, radius 8 and center lies quadrant IV...
The answer is (x-8)^2 + (y +8)^2 = 64

I just dunno how to get this asnwer so could somone explain or show their work...thanks.

2007-11-05 08:37:08 · 2 answers · asked by Green C 1

find the volume of the solid generated by rotating the circle (x-10)^2 + y^2 = 36 about the y-axis.

basically all i can do is solve for y. i just don't know what to do afterwards.

y = (-x^2 + 20x - 64)^(1/2)

2007-11-05 08:16:12 · 2 answers · asked by Anonymous

please help me

2007-11-05 08:15:38 · 10 answers · asked by Patrick T 1

How would I go about doing this, and am I supposed to divide...
Here's the problem written out:
3x^2 - 6x - 45
__________
x^2 - 25

2007-11-05 08:12:05 · 3 answers · asked by Anonymous

i have a question on my chem homework that i cant figure out. i really dont understand significant figures. the 0s confuse me because inever know when they are supposed to count. anyone who knows about sigfigs please help! lol
heres the question:

4. How many significant figures are found in each of the following:
a._____6.0080

b._____5.000 x1034

c._____0.00678

d._____56.90

e._____6,000,000

thanks! (:

2007-11-05 08:08:49 · 8 answers · asked by Manda 2

His parents gave him some candies as birhtday present. His grandparants gave him twice as many candies. And other children who attended the party ate three times as many of his candies.

How many candies has the boy ather his birthday party?

2007-11-05 08:04:08 · 4 answers · asked by Alexander 6

2007-11-05 07:58:19 · 6 answers · asked by Anonymous

x - 2y - z = 3
x + y +2z = 9
2x + 3y + z = 0

show work please. :) THANKS!!!

2007-11-05 07:51:58 · 1 answers · asked by soccer81 2

I know how to construct a triangle with 3 given lenghts using compass, but a kite, which supposedly has 4 sides and we are gicen lenghts to 3?
Im trying to remember exactly what lenghts were given in the practise paper today but they were something like this:
Two side were 6cm and 4.8 and the length of the shorter diagonal was 4.2cm. If these lenghts seem impossible to do, then could someone explain to me how i'd go about this question?

2007-11-05 07:51:08 · 3 answers · asked by Starmate 1

If mother is four years younger than the father, by how many years sister is younger than her brother?

2007-11-05 07:44:54 · 26 answers · asked by Alexander 6

2007-11-05 07:44:44 · 3 answers · asked by Ms.Shea 1

i dont understand how to do this!? can someone please help me out.. its due in 2 daysss!!

10% of the population is left-handed. find the following probilities..
a) out of 4 people selected, at least 2 are left-handed
b) out of 6 people exactly 3 are left handed
c) if the % is actualy 11.3%, what is the probability hat if you pick 5 people, al will be left handed?

2007-11-05 07:39:53 · 2 answers · asked by Anonymous

2007-11-05 07:33:10 · 5 answers · asked by Anonymous

I know this sounds crazy but I've used a calculator for the past 10 years and now that I'm in uni they won't let me and I don't remember how to do multiply or divide! I can do the very basic stuff but how would you multiply something like 2 x .02? Or divide 200 by 45?

Thanks for the help!

2007-11-05 07:25:27 · 13 answers · asked by Simon F 2

jims second test score was 8 points higher than his first test score. his third score was 88. he a b average (between 80-89 inclusive)for the three tests.

2007-11-05 07:22:45 · 1 answers · asked by clcsexyma1 1

2007-11-05 07:19:09 · 6 answers · asked by btammy99 1

the lengths of an isosceles triangle are integers. the base is half as long as each leg.

2007-11-05 07:19:04 · 1 answers · asked by clcsexyma1 1

I have a non calculator maths gcse exam tomorow, and a question similar to this is bound to come up: I have added a link please could you solve and explain how its done, thank you soo much.
http://img.photobucket.com/albums/v201/starmate/mathsQ13.jpg

2007-11-05 07:17:20 · 3 answers · asked by Starmate 1

If the graph of f contains the points ( -1, 3), ( 0, 4) and ( 2, -7) list the points that would be found on the graphs of each of the following functions:
a) f (x – 3)
b) f (x) + 3

2007-11-05 07:09:03 · 3 answers · asked by Anonymous

I'm in a class with two seperate parts. Lets call them part a and part b.

Part A=80% of grade
I got 290/330 points

Part B=20% of grade
I got 90/105 points

What will I get overall?

2007-11-05 07:08:44 · 5 answers · asked by Anonymous