### Author Topic: Web bonus problem--Week 3  (Read 8331 times)

#### Catherine Yue

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##### Re: Web bonus problem--Week 3
« Reply #15 on: January 22, 2018, 10:12:39 PM »
a. y=sint/3+c/(sint)^2
b. y=sint/3
c. y=sint/3

#### Tiange Gao

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##### Re: Web bonus problem--Week 3
« Reply #16 on: January 22, 2018, 10:19:26 PM »
The attached is my solution. Thank you

« Last Edit: January 22, 2018, 10:33:51 PM by Tiange Gao »

#### Kaiying Jiang

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##### Re: Web bonus problem--Week 3
« Reply #17 on: January 22, 2018, 10:27:45 PM »
The final answer is:(detail steps are in attachment)
a. y=1/3*sint+c*[sin(t)]^(-2)
b. When c=0, y=1/3*sin(t)
c. When y=1/3*sin(t), definable on negative infinity to positive infinity, and periodic of 2∏, which is 2 times of Pi.

« Last Edit: January 22, 2018, 10:40:24 PM by Kaiying Jiang »

#### Shirley Wen

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##### Re: Web bonus problem--Week 3
« Reply #18 on: January 22, 2018, 10:30:57 PM »
« Last Edit: January 22, 2018, 10:40:25 PM by wenyaru1 »

#### Kaiying Jiang

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##### Re: Web bonus problem--Week 3
« Reply #19 on: January 22, 2018, 10:37:11 PM »

#### Zhiman Tang

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##### Re: Web bonus problem--Week 3
« Reply #20 on: January 22, 2018, 10:51:25 PM »
« Last Edit: January 22, 2018, 10:55:05 PM by zhiman tang »

#### Yilin Ye

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##### Re: Web bonus problem--Week 3
« Reply #21 on: January 22, 2018, 11:04:08 PM »
a)
y′+2cot(t)y=cos(t).
p(t)=2cot(t)
I=e^∫2cot(t)dt
=e^2∫cos(t)/sin(t)dt
=e^2ln|sin(t)|
=e^ln|sin(t)|^2
=sin(t)^2

sin(t)^2y′+2cot(t)sin(t)^2y=cos(t)sin(t)^2

(sin(t)^2y)'=cos(t)sin(t)^2
sin(t)^2y=∫cos(t)sin(t)^2dt
=1/3sin(t)^3+c
y=1/3sin(t)+csin(t)^-2

b)let c=0  y=1/3sin(t)
c)let c=0  y=1/3sin(t)

#### Shiyi Hou

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##### Re: Web bonus problem--Week 3
« Reply #22 on: January 22, 2018, 11:12:03 PM »

#### Yuming Song

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##### Re: Web bonus problem--Week 3
« Reply #23 on: January 22, 2018, 11:20:42 PM »

#### Jiayun Huang

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##### Re: Web bonus problem--Week 3
« Reply #24 on: January 22, 2018, 11:28:08 PM »

#### Ge Shi

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##### Re: Web bonus problem--Week 3
« Reply #25 on: January 22, 2018, 11:35:40 PM »
« Last Edit: January 23, 2018, 12:12:47 AM by Ge Shi »

#### Yatong Yu

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##### Re: Web bonus problem--Week 3
« Reply #26 on: January 22, 2018, 11:43:54 PM »

#### Ge Shi

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##### Re: Web bonus problem--Week 3
« Reply #27 on: January 22, 2018, 11:49:46 PM »
« Last Edit: January 23, 2018, 12:15:11 AM by Ge Shi »

#### Jiayuwjy Wu

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##### Re: Web bonus problem--Week 3
« Reply #28 on: January 22, 2018, 11:50:22 PM »

#### Roberto Hechen

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##### Re: Web bonus problem--Week 3
« Reply #29 on: January 22, 2018, 11:57:21 PM »