#Y2 trig Rsin(x+a) and that

83 messages · Page 1 of 1 (latest)

keen flume Jan 6, 2023, 4:26 PM

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Anyone know how to solve 5 ii. b)

scenic holly Jan 6, 2023, 4:27 PM

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keen flume Anyone know how to solve 5 ii. b)

so yuck

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but

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can you see any relation between that monster and

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the things youve had to deal with before in the question

keen flume Jan 6, 2023, 4:27 PM

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kinda

scenic holly Jan 6, 2023, 4:28 PM

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what do you see

keen flume Jan 6, 2023, 4:28 PM

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5cosx + 3cosx

scenic holly Jan 6, 2023, 4:28 PM

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yeah so

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we wanna try find a way to

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convert 1/3 b - 40 into theta - 60 right

keen flume Jan 6, 2023, 4:28 PM

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for i) i got 7sin(x + 51.8)

scenic holly Jan 6, 2023, 4:28 PM

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and 1/3 b + 20 into theta right?

keen flume Jan 6, 2023, 4:29 PM

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wym?

scenic holly Jan 6, 2023, 4:29 PM

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cuz if we can do that we can just use other parts

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well like

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we have 5cos(theta - 60) before

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and now we have 5cos(1/3 b - 40)

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so we kinda want to find a way to turn our

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1/3 b - 40 into theta - 60

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right?

keen flume Jan 6, 2023, 4:30 PM

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ohhh

scenic holly Jan 6, 2023, 4:30 PM

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same for 1/3 b + 20 into theta

keen flume Jan 6, 2023, 4:30 PM

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how would we do that

scenic holly Jan 6, 2023, 4:30 PM

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because of the 2nd 3cos(theta)

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well

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this is the tricky part

keen flume Jan 6, 2023, 4:30 PM

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wait lemme try

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ill lyk when i'm stuck

scenic holly Jan 6, 2023, 4:30 PM

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yep ok

keen flume Jan 6, 2023, 4:32 PM

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nvm i don't know what i'm doing

scenic holly Jan 6, 2023, 4:32 PM

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ok so

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i think a reasonable first guess would be to

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lets just say theta is 1/3 b

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is theta is 1/3 b what does the equation become instead

keen flume Jan 6, 2023, 4:33 PM

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5cos(theta - 40) + 3cos(theta+20) = 3

scenic holly Jan 6, 2023, 4:33 PM

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mmmm

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so while its not like weve seen before

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its pretty damn close right

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can you see how close 5cos(theta - 40) + 3cos(theta+20) is to 5cos(theta - 60) + 3cos(theta)

keen flume Jan 6, 2023, 4:35 PM

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shifted 20 degrees to the left

scenic holly Jan 6, 2023, 4:35 PM

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perfect exactly

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so while theta = 1/3 b isnt quite right

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1/3 b + 20 = theta

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that looks more right

keen flume Jan 6, 2023, 4:35 PM

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ahh okay i think i understand it now

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thank you

scenic holly Jan 6, 2023, 4:35 PM

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nw!

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lmk if you need more help after

keen flume Jan 6, 2023, 4:36 PM

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i'll try solve it now

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alright sure. thank you so much

keen flume Jan 6, 2023, 4:51 PM

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i've gotten a value for 1/3 b + 71.8 which is 25.37

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but idk how to solve it

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@scenic holly

scenic holly Jan 6, 2023, 4:54 PM

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well

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1/3 b + 71.8 = 25.37

keen flume Jan 6, 2023, 4:54 PM

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i got -139.29

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but thats a negative value

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i need the smallest positive

scenic holly Jan 6, 2023, 4:55 PM

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ok so

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we need to think about sine then

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if you have a value for sine so like

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60 degrees

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how can you find others

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i think i explained that bad but

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so if say sin(x) = 1/2

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how might we find others?

keen flume Jan 6, 2023, 4:57 PM

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oh yh using cast

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is my cast diagram correct

scenic holly Jan 6, 2023, 5:02 PM

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er

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idk i dont use cast

keen flume Jan 6, 2023, 5:10 PM

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what do you do

scenic holly Jan 6, 2023, 5:19 PM

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add 90 or whatever i need

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do 180-answer

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or add 360

keen flume Jan 6, 2023, 5:32 PM

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i got the answer

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finally

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so what i did was 300 - 25.37

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then 274.63 - 71.8

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then 202.83 * 3

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then 608.49 - 360

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which is 248.5