Notifications

Clear all

Integration with trig identites qs

Last Post

Posts: 4

Arjen

Topic starter

Mar 15, 2020 9:53 am

(@arjen)

New Member

Joined: 3 years ago

Question 8, I'm not sure how to even start the qs

Please show working I would be very grateful

Topic Tags

7 Replies

Abdurrahman

LSC Tutor

(@abdurrahman)

Joined: 3 years ago

Reputable Member

Posts: 284

Mar 15, 2020 10:01 am

Reply to

Arjen

@arjen i used integration by parts but just got lost along the way ? ?

Think deeply about simple things. The best way to learn is by asking questions.

Posts: 274

Further_Maths_Student

ExamQA+

Mar 15, 2020 12:05 pm

(@further_maths_student)

Reputable Member

Joined: 3 years ago

I would start it like this

by parts, then you might have to do by parts two more times

Abdurrahman

LSC Tutor

(@abdurrahman)

Joined: 3 years ago

Reputable Member

Posts: 284

Mar 15, 2020 12:30 pm

Reply to

Further_Maths_Student

@further_maths_student yeah i started in a similar way, however my "v" is different to yours, how did you get v? Are you sure its correct because I got v = 1/2(cot(x))^2 (+c) using inspection as well as substitution to double check. But other that, your absolutely right! Thank you man!! ?

Think deeply about simple things. The best way to learn is by asking questions.

Abdurrahman

LSC Tutor

(@abdurrahman)

Joined: 3 years ago

Reputable Member

Posts: 284

Mar 15, 2020 1:17 pm

Reply to

Abdurrahman

@zeeshan @zubair sir could you please have a go?

Think deeply about simple things. The best way to learn is by asking questions.

Further_Maths_Student

ExamQA+

(@further_maths_student)

Joined: 3 years ago

Reputable Member

Posts: 274

Mar 15, 2020 2:46 pm

Reply to

Abdurrahman

@abdurrahman

your v is fine, both of ours differentiate to give cosec^2x cotx.

I got v by inspection (reverse chain rule) so if you differentiate -cosec^2x, you will get 2cosec^2xcotx (i pretended the 2 was with the trig functions instead of being with x^2, and I just realised that i made a mistake because I wrote positive cosec^2x. I’m gonna send the solution I wrote anyway but keep in mind there are sign errors