Science & Mathematics - 20 October 2007

please help me solve this identity

cos(α+β)cos(α-β)=cos²β-sin²-α

thankyou

2007-10-20 09:59:19 · 1 answers · asked by xyz 1 in Mathematics

2007-10-20 09:58:39 · 6 answers · asked by -- 1 in Astronomy & Space

Caproic acid (molar mass = 116g/mol) is composed of C, H and O atoms. Combustion of a 0.225g sample produces 0.512g CO2 (carbon dioxide) and 0.209 H20 (water).
a) Find empirical formula of caproic acid
b) Find molecular formula of caproic acid

2007-10-20 09:51:23 · 1 answers · asked by Questionnaire 3 in Chemistry

2007-10-20 09:50:34 · 9 answers · asked by acuraboy1978 2 in Mathematics

How many moles of ions are present in water solutions prepared by dissolving 0.4132 mol of
a) magnesiom chloride
b) manganese (II) nitride
c) cobalt (III) nitrate
d) iron (II) permanganate

2007-10-20 09:47:02 · 2 answers · asked by hsm 4 in Chemistry

2007-10-20 09:45:55 · 3 answers · asked by Anonymous in Chemistry

give the exact value of the expression without using a calculator.

a) csc^-1 (sec(π/3))

b) cot^-1 (-(3^(1-2)/3)

c) tan^-1 (-(3^(1-2)/3)

can anyone please help me solve these and show how to work them out.
Thank you.

2007-10-20 09:43:25 · 1 answers · asked by abc 1 in Mathematics

2007-10-20 09:40:17 · 2 answers · asked by Dee B 1 in Zoology

2007-10-20 09:38:52 · 3 answers · asked by Anonymous in Astronomy & Space

I have to design a model car that can follow a maze constructed from metallic tape stuck to the floor. I was wondering if anyone had any ideas about how i could detect the foil tape so that my car won't cross any of the "walls" of the maze. A method to detect the foil tape needs to be selected with the reasons for the choice. The car will be controlled by an eight bit microcontroller.

2007-10-20 09:37:11 · 3 answers · asked by Iain M 1 in Engineering

a) What is the approximate relative atomic mass of this element?
b) Identify X.

2007-10-20 09:36:13 · 5 answers · asked by Anonymous in Chemistry

2007-10-20 09:35:12 · 2 answers · asked by carmellabella 1 in Mathematics

2007-10-20 09:32:59 · 1 answers · asked by GEEK 1 in Biology

2007-10-20 09:32:27 · 5 answers · asked by Anonymous in Zoology

2007-10-20 09:31:10 · 2 answers · asked by Anonymous in Other - Science

Why is there so much focus on breast cancer when it's heart disease that's the number one killer of women?

2007-10-20 09:22:39 · 5 answers · asked by soulestada 4 in Medicine

If you're adding two chemical equations, and you have two of the same molecules, one on reactant side, and one on the product side, BUT they have different states... can you cancel them out?

E.g. H2O(l) on reactants, H2O(g) on products.

2007-10-20 09:21:24 · 2 answers · asked by de4th 4 in Chemistry

If you had a word problem that said something like:

If the ( can't remember what it is) Opening is 76 feet above sea level, and the closing is 314 feet below sea level. What is the total lengh( can't remember what the thing is)

What would be the answer, thanks

2007-10-20 09:20:09 · 12 answers · asked by Foretold F 2 in Mathematics

http://img134.imageshack.us/my.php?image=earth1er2.png

http://img509.imageshack.us/my.php?image=earth2ch4.png

http://img87.imageshack.us/my.php?image=earth3op8.png

http://img87.imageshack.us/my.php?image=earth4qt3.png

http://img150.imageshack.us/my.php?image=earth5gs7.png

http://www.terremoto.ca/images/milky_way.jpg

http://www.space-art.co.uk/images/artwork/diagrams/Our-Place-in-Space.jpg

Please feel free to post any diagrams you have. Especially of our galaxy compared to the Universe.

2007-10-20 09:19:38 · 4 answers · asked by Anonymous in Astronomy & Space

A reagent bottle is labeled 0.450 M K2CO3. If 50.0 mL of this solution is added to enough water to make 125 mL of solution, what is the molarity of the diluted solution?

2007-10-20 09:18:54 · 2 answers · asked by hsm 4 in Chemistry

The pilot of an aircraft wishes to fly due west in a 50.0km/h wind blowing toward the south. The speed of the aircraft in the absence of wind is 305 km/h.
a) In what direction should the aircraft head?
b) What is the speed of the aircraft relative to the ground?

2007-10-20 09:18:01 · 1 answers · asked by brainless storm 1 in Physics

A ball is thrown upward from the roof of a building 100 m tall with an initial velocity of 20 m/s. When will the ball reach a height of 80 m?

2007-10-20 09:07:16 · 5 answers · asked by Mommy-fied 5 in Mathematics

Ok, so for this lab, we had to dry some silver chloride in a Goch crucible in an oven. Then we were supposed to take it out of the oven, and make sure to let the crucible and silver chloride cool before weighing it. One of the follow-up questions for the lab is if the crucible and silver chloride were weighed while still hot, would the percent yield of silver from the original alloy be higher or lower than the true value and why (we were given an alloy with silver, and we extracted the silver into silver chloride, so that we weigh the silver chloride and use calculations to figure out the amount of silver present in the original alloy). Basically I'm pretty sure the question means if the weight of the crucible and silver chloride will be more or less than at room temperature and why, because this is what would affect the percent yield in the calculations.

2007-10-20 09:05:43 · 1 answers · asked by ajfmf90 2 in Chemistry

2007-10-20 09:04:02 · 2 answers · asked by alejandro g 1 in Mathematics

i know i'm morbid... but i wanna know *shrugs*

2007-10-20 09:02:10 · 4 answers · asked by Anonymous in Biology

2h-6/6 =2/3

write a problem that can be solved by using similar triangles, solve the problem with pictures

2007-10-20 09:01:52 · 4 answers · asked by LuvTheJonasBrothers 2 in Mathematics

find the missing side of the right triangle (round to the nearest tenth if neccasary)
side a=4 side b=7 side c= ?
side a=12 side c=15 side b=?
side b=9 side c=20 side a=?
side a=0.6 side b=0.8 side c=?

I think the last one is 1 im not sure tho

2007-10-20 08:58:02 · 4 answers · asked by LuvTheJonasBrothers 2 in Mathematics

2007-10-20 08:53:04 · 12 answers · asked by silvernonferous 1 in Other - Science

The equation h = -16t ^2 + 112t gives the height of a narrow, shot upward from the ground with an initial velocity of 112 ft/s, where t is the time after the arrow leaves the ground. Find the time it takes for the arrow to reach a height of 180 ft.

2007-10-20 08:52:01 · 2 answers · asked by Mommy-fied 5 in Mathematics

2007-10-20 08:51:34 · 8 answers · asked by Jeff 3 in Zoology