amhishaw
2 cos theta = 1, find all solutions



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Brittni0605
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Step by step help?

amhishaw
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yes

Brittni0605
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Ok, so think of theta as a variable

Brittni0605
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if theta was an 'x' how would you solve?

amhishaw
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to be honest I have no clue.

shaik0124
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2 cos theta=1
cos theta=1/2
theta=cos inverse(1/2)
theta=60degrees

amhishaw
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ok, so i would divide 2 from both sides?

Brittni0605
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Yes.

Brittni0605
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dw:1357848817327:dw

Brittni0605
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Now, you know cos theta equals 1/2..now you want to find theta, do you know how?

amhishaw
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oh! okay and would I just look for cos (x) value on the unit circle right?

Brittni0605
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Umm, you could do that. But im not sure if you would have the unit circle with you on your tests.

Brittni0605
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There is another way to do it, if you have a graphing calc or if you memorized the cos and sin values of the major degrees on the circle.

amhishaw
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well no lol my precal teacher was trying to explain how to but I couldn't understand

amhishaw
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without it*

Brittni0605
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Ohh, ok. Well try to memorize the major degrees..like 30, 60, 45, 90, 180, 270, 360.

Brittni0605
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But if you were to use your unit circle, you would look for the degrees with a cos (x value) of 1/2

Brittni0605
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dw:1357849233772:dw

amhishaw
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ok, so would i use ALL of the radian values of cos 1/2?

Brittni0605
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do you know the cos and sin values of the angles I drew?

Brittni0605
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Yes, all of the values, bc the problem says find ALL

amhishaw
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I know most of them

amhishaw
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thank you so much, you've been a lot of help

amhishaw
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so the solutions would be pi/3 and 5pi/3?

Brittni0605
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Yes.