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Mathematics 23 Online
OpenStudy (anonymous):

Somebody help! Will FAN and MEDAL Simplify the trig expression

OpenStudy (anonymous):

OpenStudy (anonymous):

@jim_thompson5910

OpenStudy (anonymous):

@satellite73

jimthompson5910 (jim_thompson5910):

Start off with the idea that cos^2 + sin^2 = 1

jimthompson5910 (jim_thompson5910):

what is cos^2 in terms of sin?

OpenStudy (anonymous):

Hmm, like the reciprocal identity?

jimthompson5910 (jim_thompson5910):

how would you isolate cos^2

jimthompson5910 (jim_thompson5910):

in the equation cos^2 + sin^2 = 1

OpenStudy (anonymous):

cos^2= sin^2 + 1 ?

jimthompson5910 (jim_thompson5910):

close but no

OpenStudy (anonymous):

is it minus one?

jimthompson5910 (jim_thompson5910):

cos^2 = 1 - sin^2

OpenStudy (anonymous):

Ohh

OpenStudy (anonymous):

Thats one of the indentities

jimthompson5910 (jim_thompson5910):

yes, the pythagorean identity

OpenStudy (anonymous):

so that would mean cos^2 is equal to 1

jimthompson5910 (jim_thompson5910):

no

OpenStudy (anonymous):

Oh okay, I'm lost again then

jimthompson5910 (jim_thompson5910):

do you see how cos^2 + sin^2 = 1

OpenStudy (anonymous):

yes

jimthompson5910 (jim_thompson5910):

do you see how I'm getting cos^2 = 1 - sin^2

OpenStudy (anonymous):

yes

jimthompson5910 (jim_thompson5910):

So... \[\Large \frac{\cos^2(\theta)}{1 - \sin(\theta)}\] \[\Large \frac{1-\sin^2(\theta)}{1 - \sin(\theta)}\] what's next?

OpenStudy (anonymous):

Simplify by canceling out?

jimthompson5910 (jim_thompson5910):

that comes later

OpenStudy (anonymous):

I'm not sure then

jimthompson5910 (jim_thompson5910):

factor the numerator

OpenStudy (anonymous):

Like (sin) (sin)?

jimthompson5910 (jim_thompson5910):

kinda

jimthompson5910 (jim_thompson5910):

you'd use the difference of squares rule

OpenStudy (anonymous):

Okay I factored it, well I tried anyway.. is it 1-sin?

jimthompson5910 (jim_thompson5910):

check out this http://www.purplemath.com/modules/specfact.htm

OpenStudy (anonymous):

(1-csc)(1+csc) ?

jimthompson5910 (jim_thompson5910):

closer but no

OpenStudy (anonymous):

Or am I just not getting this at all?

OpenStudy (anonymous):

Aw poop, okay hold on

OpenStudy (anonymous):

Actually, never mind, I don't think I am getting it

jimthompson5910 (jim_thompson5910):

use a^2 - b^2 = (a-b)(a+b)

jimthompson5910 (jim_thompson5910):

a = 1 b = sin(theta)

OpenStudy (anonymous):

(1-sin)(1+sin) ?

jimthompson5910 (jim_thompson5910):

yep

OpenStudy (anonymous):

YES

jimthompson5910 (jim_thompson5910):

you'll notice something cancelling

OpenStudy (anonymous):

Okay, I should get 1+sin

jimthompson5910 (jim_thompson5910):

yep

OpenStudy (anonymous):

Thank you so much! (:

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