Mathematics - 5 September 2007

HI! I'm pissed, as usual, about trigonometry. This time, it's about the reduction formula, a.k.a. the most idiotic thing I've ever seen in my life. I thought that all was fine, but now I've come across some real problems. First of all, my book does not explain how to use the reduction formula. All it does is give the formula and then show 1 problem worked out.

What I've surmised from that (and it has served me well thus far) is:

√(a² + b²)sin( x + α)

Great. I get the whole "√(a² + b²)sin( x" part, but I seem to be having trouble with the "+ α" aspect of it.

What I would guess, solely from my stupid book, is that to get α, you find cos α by doing a/[√(a² + b²)]. I need to know:

1) How do you know which value of α to use? Often times there is more than one angle for which cos = a/[√(a² + b²)].

2) What do you do when the problem is NOT in the form of a sin x + b cos x, but rather a sin x - b cos x? What about if a is negative?

Thank you so much! I'll pick a best answr!

2007-09-05 06:51:18 · 2 answers · asked by Anonymous

I need to obtain a graphing calculator for Calculus. What is the best one to get? Theres so many I don't know where to begin.

2007-09-05 06:46:34 · 10 answers · asked by Fashionisto Billy 4

2007-09-05 06:43:41 · 8 answers · asked by JacQuan E 1

My physics teacher told me that 1 = 2 because:
0 = 0
a^2 - a^2 = a^2 - a^2
a(a-a) = (a+a)(a-a)
cancel out (a-a)
a = a+a
divide by a
1=2????
how is this possible and how can I disprove it??

2007-09-05 06:42:05 · 14 answers · asked by Hehe 2

Simplify:

cos(A+pi/2)+sin(A+pi/2)

2007-09-05 06:41:26 · 5 answers · asked by Anonymous

2007-09-05 06:40:19 · 8 answers · asked by bratt200507 1

2007-09-05 06:39:13 · 5 answers · asked by Cortez M 2

An insulated tank is filled with a solution containing radioactive cobalt. Due to the radioactivity, energy is released and the temperature T (in deg C) of the solution rises with time t (in h). The following equation expresses the relation between temperature and time for a specific case: dT=(20.0-2.50t)dt. If the initial temperature is 65 degrees C, what is the temperature 12 hours later?

2007-09-05 06:37:19 · 3 answers · asked by Anonymous

/ means fraction
Can not find LCD

2007-09-05 06:36:28 · 9 answers · asked by Gucci 2

it only displays my answers in fraction format and not in decimal format, how do i fix this?

2007-09-05 06:34:21 · 13 answers · asked by Anonymous

1. If arizona is 114,000 square miles, which accounts for 3.07% of the United States. How big is the united states? How did you do this?

2. If a computer cost $1750.00 and the tax was 8.05% how much is the tax?

2007-09-05 06:32:12 · 8 answers · asked by Anonymous

2007-09-05 06:29:49 · 4 answers · asked by Arkesha S 1

Flying with the wind, a plane takes 1hr to go from city A to city B. Flying against the wind, the plane takes 2hrs to go from city B to city A. The trip from A to B is 200 miles. What is the speed of the plane and the wind?
a = speed of plane, w = speed of plane

I've only been able to get this far..
(a+w)*1=200
(a-w)*2=200

a+w=200
2a-2w=200
I know I need to substitute the problems then plug that number back in to get the second answer, but how do I do it?

2007-09-05 06:28:41 · 8 answers · asked by tina 3

What is the chance of having no pair of cards of the same rank next to each other in a hand of five cards (from a deck of 52 cards) ? According to me it's impossible to calculate unless you check all the possibilities.

2007-09-05 06:27:58 · 5 answers · asked by ?????? 7

The sales (S) of a product as a function of the time (t) (in weeks) is given by S=[2300(5t+1)] / (2t+5). Find the instantaneous rate of change of (S) with respect to (t) for t= 9 weeks.

2007-09-05 06:27:55 · 2 answers · asked by Anonymous

ok, once again, i don't understand what my teacher has done here.

6x^3y-24x^2y
-------------------
9x^2y^2+27xy^2


he simplified, so that we'd have:

2x-24x^2y
--------------
3y+27xy^2


but then he wrote
=2x(x-4)
-------------
3y(x+3)


i understand that he just factored, but why is it just (x-4) and (x+3). i missed the explanation.

2007-09-05 06:25:00 · 4 answers · asked by alexie. 4

Twice the sum of a number and 3 is the same as 1 subtracted from the number. find the number??

2007-09-05 06:19:46 · 12 answers · asked by Desiree S 1

how many litres makes a glass of water?

2007-09-05 06:19:38 · 7 answers · asked by sendfrancis 1

according to some certain rule, which number should be put in it, why?
12（56）16
17（ ）21

2007-09-05 06:16:41 · 6 answers · asked by Gabriel 1

I've got this quadratic to solve as part of a problem but can't do it- any help please?!
3s^2 - 925s + 7500 = 0
Obviously you need to use the general solution but I can't do this with b being negative. Please help.

2007-09-05 06:07:16 · 7 answers · asked by Ash 2

use dimensional analysis to change:
a. 20.8 tons to pounds
b.504 minutes to weeks
c. 2500 centimeters per second to kilometers per hour

2007-09-05 05:58:14 · 5 answers · asked by Anonymous

2007-09-05 05:54:34 · 9 answers · asked by shawna 2

I don't really understand it. If someone could explain it that'd be great.

4 - x = 11

THANKS!!

2007-09-05 05:52:36 · 22 answers · asked by jacobsbeffie 1

A triangle ABC, Angle A=60. Prove that BC^2=AB^2 + AC^2 - (AB.AC) without using cosine rule.

Kindly help me.

2007-09-05 05:51:13 · 2 answers · asked by anand brar 2

The sum of twonumbers is33. Twice the first number minus the second number equals 18.Find both numbers

2007-09-05 05:44:05 · 8 answers · asked by Anonymous

2007-09-05 05:40:24 · 7 answers · asked by shawna 2

Solve by either the substitution or the addition-or-subtraction method.

2m = n-3
3m = 2n-9

Thanks for the help!

2007-09-05 05:31:32 · 10 answers · asked by Nerds Rule! 6

as in f(x-8)=square-root of x-8 + 8 + 2 = ??

2007-09-05 05:26:24 · 3 answers · asked by em.four 2

2007-09-05 05:25:43 · 21 answers · asked by Anonymous

GOOD MORNING EVERYONE!!! I hope you all slept well.....

I need some help with Algebra, I need to find a website that allows me to compare all cell phone plans accurately, and show many prices that are fixed and many that are variable. I know it's a lot to ask, but I have been looking for a while and nothing has turned up, any help is great. Thanks guys, have a great day!

2007-09-05 05:20:38 · 2 answers · asked by Anonymous