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Mathematics 14 Online
OpenStudy (laddiusmaximus):

(sinx/(1+cosx)) +((1+cosx)/sinx) totally lost

OpenStudy (anonymous):

What do you have to do? prove it?

OpenStudy (laddiusmaximus):

yeah=2cscx

myininaya (myininaya):

combine the fractions by finding a common denominator

OpenStudy (laddiusmaximus):

yeah i got that, but what do I use, sinx? or 1+cosx?

OpenStudy (anonymous):

I'm working on it

OpenStudy (anonymous):

The Common Denominator will be sinx(1+cosx)

myininaya (myininaya):

what do you mean? how to combine these fractions: 2/3+5/7

OpenStudy (laddiusmaximus):

so the common denominator is (sinx)1+cosx?

myininaya (myininaya):

sinx(1+cosx)

OpenStudy (anonymous):

yes that is the common denom

OpenStudy (laddiusmaximus):

okay so now I have (sinx^2x(1+cosx)/sinx(1+cosx)) + (sinx(2+cos^2x)/sinx(1+cosx))?

myininaya (myininaya):

you will have (sinx)^2+(1+cosx)^2 in the numerator and sinx(1+cosx) is the denominator

OpenStudy (laddiusmaximus):

sin^2x on both sides?

OpenStudy (anonymous):

I think you should have this so far: \[\sin^2x + (1+cosx)^2/sinx(1+cosx)\]

myininaya (myininaya):

ok look at your first fraction. what does the bottom lack so that it has the same denominator as the 2nd. sinx, right?

myininaya (myininaya):

multiply both the top and bottom by sinx on the first fraction

OpenStudy (laddiusmaximus):

hmm i had [\sin^2x(1+cosx)+sinx(2+\cos^2x)/sinx(1+cosx)\]

myininaya (myininaya):

now look at the 2nd fraction what does the bottom lack so that it has the same denominator as the first fraction, (1+cosx), right?

myininaya (myininaya):

so multiply the top and bottom of the 2nd fraction by (1+cosx). Now the fractions have the same denominator, you can write it as one fraction now

OpenStudy (laddiusmaximus):

I follow you so far.

myininaya (myininaya):

so we have [sinx*sinx+(1+cosx)(1+cosx)]/[sinx(1+cosx)]

myininaya (myininaya):

[(sinx)^2+1+2cosx+(cosx)^2]/[sinx(1+cosx)]

OpenStudy (anonymous):

I think I got the complete answer/proof

myininaya (myininaya):

what is (sinx)^2+(cosx)^2

OpenStudy (anonymous):

=1

myininaya (myininaya):

lol gj, but i was laddius

OpenStudy (anonymous):

oops sorry

myininaya (myininaya):

but i was asking*

myininaya (myininaya):

do you still follow laddius

OpenStudy (laddiusmaximus):

so the numerator becomes sin^2x + (1+cosx)^2?

OpenStudy (anonymous):

yes

myininaya (myininaya):

now foil that (1+cosx)^2

OpenStudy (anonymous):

exactly lol

OpenStudy (laddiusmaximus):

so now its 1+2cosx+cosx^2?

OpenStudy (anonymous):

yes!

myininaya (myininaya):

+(sinx)^2

myininaya (myininaya):

now do you see (sinx)^2+(cosx)^2 anywhere in that numerator

OpenStudy (laddiusmaximus):

ahhhhh pythagorean

myininaya (myininaya):

what do you have now?

OpenStudy (laddiusmaximus):

so now I have 2+2cosx/sinx(1+cosx)

myininaya (myininaya):

ok what does the numerator terms have in common

OpenStudy (laddiusmaximus):

2?

OpenStudy (anonymous):

HAHA ignore my last 3 posts..

myininaya (myininaya):

does anything cancel?

myininaya (myininaya):

jp?

OpenStudy (laddiusmaximus):

the 2s cancel, right?

myininaya (myininaya):

no the 1+cosx do

myininaya (myininaya):

so you have 2/sinx

myininaya (myininaya):

which is ....

OpenStudy (laddiusmaximus):

I have 2+2cosx in the numerator

OpenStudy (laddiusmaximus):

cosx+cosx= 2cosx, right?

myininaya (myininaya):

didnt you say the numerator terms had a 2 in common so factor that out in you have 2(1+cosx)/[sinx(1+cosx)]

OpenStudy (laddiusmaximus):

crap then the (1+cosx) cancel out and im left with 2cscx

myininaya (myininaya):

BINGO!

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