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marinejas marinejas
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3 years ago
a) sin 2pi/3
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bio_manbio_man
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#1
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3 years ago
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marinejas Author
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#2
3 years ago
do you know if there's some kind of chart that states when to subtract pi , or add pi from the following angle like in all 4 quads it would be a lot easier for me, because every time I'm doing questions like these I'm always messing up that specific part, if not that's okay, just wanted to know because I'm getting confused with this. Frowning Face
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#3
Educator
3 years ago
Maybe these video would help? Watch them carefully.

#1



#2
marinejas Author
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#4
3 years ago
okay I tried doing b) which is cos 5pi/4 and I did 5pi/4 - pi and got 1/4pi which led me to one of the special triangles, one of them having an angle of pi/4, I then did cos = adj/hyp, cos= 1/√2 and got -0.7602 (added a negative bc cosine is negative in the 3rd quad) but got that wrong, the answer was supposed to be -√2/2, so wasn't sure where I went wrong.
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#5
Educator
3 years ago
1/sqrt(2) is the same as sqrt(2)/2

They look different because 1/sqrt(2) has been "rationalized", which is a mathematical technique used to remove the square root from the denominator. I can show you how to rationalize if you like, but besides that congrats, you got it!!!

PS: 1 in every 4 teachers will request you to rationalize
marinejas Author
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#6
3 years ago
sorry for the late reply, but yes I realized my mistake, thanks again! Slight Smile
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#7
Educator
3 years ago Edited: 3 years ago, bio_man
Remember, it's not a "mistake". Rationalizing the denominator is totally optional. Watch the videos below for more insight:

Video 1 (Simpler stuff)



Video 2 (More complicated stuff)
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