lilsis76
how can i determine which of the two trigonometric values is larger in a, b, and c ?
a) cos pi/12 or sin pi/12
b) cos 18 degrees or cos 54 degrees
c) cos 320 degrees or sin 290 degrees
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ChmE
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look up the unit circle
ChmE
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for cos. The higher the degree up to 90 the lower the value. from 90 to 180 the value increases. for sin it is the opposite. **UNIT CIRCLE**
lilsis76
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okay. im checking it out
lilsis76
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|dw:1355083613247:dw|
lilsis76
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okay, well for a) it says cos pi/12 and sin pi/12, how will i know where the pi/12 is??
lilsis76
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|dw:1355083788207:dw| @ChmE
ChmE
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its half of pi/6
ChmE
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cos is the x value and sin in the y value
ChmE
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you can see the the y value increases to 90 then goes back down. x value it opposite
lilsis76
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oh...okay i didnt see that. so then the cos would be larger because its sqrt3/2 ?
ChmE
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|dw:1355084128293:dw|x value is greater than the y value right. more right than up. so cos pi/12 is bigger
ChmE
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correct
ChmE
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so what is b)
lilsis76
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cool, i didnt understand this what so ever last time. let me try the next one okay. and ill give u my answer. could u tell me if its right?
so cos 18, would be larger than cos 54 right?
ChmE
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right
ChmE
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try C :D
lilsis76
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okay let me see
ChmE
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Careful because it is kind of a trick question
lilsis76
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it be 320?
lilsis76
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WAIT!, wait y
lilsis76
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haha y
ChmE
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yes. because sin is negative in this quadrant. It is a big red flag
ChmE
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sin will always be less in quadrant 4
lilsis76
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okay, so the sin would mean its smaller so that means the cos will be smaller too
ChmE
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I wouldn't say that
lilsis76
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okay thank you so much haha. im trying to correct my last test givin back to me and i got alot wrong cuz i didnt understand lots of things
ChmE
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I hope this helped. Just think of cos as the x value on the circle and sin as the y value on the circle. Always helped me