math homework help!

[Braves]

it's late at night and i really can't figure these out... please help or point in the right direction

Verify the following (write a proof)
a. cscX (cosecant X) - sinX = cosXtanX (cosX multiplied by tanX)
b. (sinA-cosA)/(secA-cscA) = cosA/cscA

solve 3cosX = 2

solve cosA = sin(270 + A)

I wish I were better at math but I just don't get these problems, or i dont' see my errors. Thx for any help

 

[Orsorum]

<<
solve 3cosX = 2
>>



cos x = 2/3
cos ^ -1 (2/3) = x

 

[Orsorum]

Bah, that's all my feeble brain can figure out... maybe tomorrow.

 

[BornStar]

cosA = sin(270+A)

A = 90 or -90

cos90 = 0
sin360 = 0

think of a) as 1/sin^2(x) - sin(x) = (cos(x)sin(x))/cos(x)

 

[shadowfaX]

<< it's late at night and i really can't figure these out... please help or point in the right direction

Verify the following (write a proof)
a. cscX (cosecant X) - sinX = cosXtanX (cosX multiplied by tanX)
b. (sinA-cosA)/(secA-cscA) = cosA/cscA

solve 3cosX = 2

solve cosA = sin(270 + A)

I wish I were better at math but I just don't get these problems, or i dont' see my errors. Thx for any help >>



yummmy, math! i'll answer but i'm sure someone will beat me to it since i don't type *that* fast...

a. cscx - sinx = (1/sinx) - sinx
= (1/sinx) - (sinx)^2/sinx
= (1 - (sinx)^2)/sinx
= (cosx)^2/sinx
= (cosx/sinx) * cosx
= cosx*tanx

b. (sinA-cosA)/(secA-cscA) ---> sorry, this one's a little long to type out in a non-confusing way, but what you can do is multiply the entire thing by (secA+cscA)/(secA+cscA) to get some cancellations and whatnot going.

c. 3cosx = 2
cosx = (2/3)
when does cosx = 2/3 ? just use arccos(2/3) to solve that.

d. cosA = sin(270 + A) --> edit: okay, this one's already solved


sorry about any fuzzy math...

 

[areohbe]

man i wish i had to do trig proofs like that again.

i'm getting absolutely screwed by the proofs we've got to do in Linear Algebra

 

[BornStar]

Oh, well that explains it. I was wondering why cscX (cosecant X) - sinX = cosXtanX (cosX multiplied by tanX) didn't look like it would actually work. Apparently everything that is in () is clarification. I couldn't figure out why he used csc and cosecant since they are the same thing... Don't look at my help for a).

 

[shadowfaX]

trig proofs... haha... i'm wishing i could do them again and i'm only in calculus.

 

[Braves]

wow, thx very much for all the help. Math used to be easy for me, but somehow it's just not as simple as multiplication tables anymore

 

[Braves]

doh, have one more in case anyone's awake right now.

if 0 smaller or equal to X, which is smaller or equal to 360, solve 3sin(squared)X - 7sinX = 6