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Mathematics 21 Online
OpenStudy (brittany16):

Simplify: (sin Θ − cos Θ) − (sin Θ + cos Θ)2 can someone help?

OpenStudy (brittany16):

hello??

OpenStudy (markkboyy):

-3

OpenStudy (markkboyy):

click best response

OpenStudy (brittany16):

thats not an answer choice

OpenStudy (brittany16):

the answer choices are: −sin2 Θ −cos2 Θ 0 −2sin(Θ)cos(Θ) − cos(Θ) + sin(Θ) − 1

OpenStudy (markkboyy):

well i dont know what to say because i got Simplify the expression. −3

OpenStudy (brittany16):

what did you do to arrive to that conclusion?

OpenStudy (welshfella):

(sin Θ − cos Θ) − (sin Θ + cos Θ)2 = sin Θ - cos Θ - ( sin^2 Θ + cos^2 Θ + 2 sin Θ cos Θ} Now sin^2 Θ + cos^2 Θ = 1 and 2 sin Θ cos Θ = sin 2Θ - can you continue?

OpenStudy (brittany16):

no, i have no idea how to do this

OpenStudy (welshfella):

Oh - no need to use that final identity

OpenStudy (welshfella):

well replace sin^2 Θ + cos^2 Θ by 1 then just simplify

OpenStudy (brittany16):

im still confused, what exactly am i simplifying

OpenStudy (welshfella):

sin Θ - cos Θ - ( sin^2 Θ + cos^2 Θ + 2 sin Θ cos Θ} = sin Θ - cos Θ - ( 1 + 2 sin Θ cos Θ}

OpenStudy (welshfella):

now distribute the negative over the parentheses and you have the answer

OpenStudy (brittany16):

-1-2sin(theta)cos(theta)?

OpenStudy (welshfella):

what happened to the first 2 terms?

OpenStudy (brittany16):

oh im sorry, let me retry

OpenStudy (welshfella):

- the distribution you did is correct

OpenStudy (brittany16):

wouldnt they just stay the same in front of what i did?

OpenStudy (welshfella):

of course

OpenStudy (brittany16):

okay, thats not an answer choice though

OpenStudy (brittany16):

can it be further simplified?

OpenStudy (welshfella):

no

OpenStudy (brittany16):

im not sure whats wrong then the answer choices are: −sin2 Θ −cos2 Θ 0 −2sin(Θ)cos(Θ) − cos(Θ) + sin(Θ) − 1

OpenStudy (brittany16):

is it the last one and its just written differently?

OpenStudy (welshfella):

Yes they could have changed the fist part to - 2 sine theta but chose not to.

OpenStudy (brittany16):

okay, thank you for all your help

OpenStudy (welshfella):

* - sin 2 theta

OpenStudy (welshfella):

yw

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