Here is the working for c, I spent a while looking at the best method to explain it. It is not an easy question, so I apologise if the solution is confusing, let me know if you have any questions :smile:

ImageUploadedByStudent Room1459983533.467249.jpg

Posted from TSR Mobile

Reply 30

Hjyu1

Anyone know where I can find more difficult polar coordinate questions that are similar to the Aqa ones?

(edited 8 years ago)

Reply 31

Qcomber

Original post by Hjyu1

Anyone know where I can find more difficult polar coordinate questions that are similar to the Aqa ones?

Go on the C3 15th june thread and there is a link there for legacy papers and find the ones called something like map-5, there are some tough questions there if you skim through those papers

Reply 32

Hjyu1

Original post by Qcomber

Go on the C3 15th june thread and there is a link there for legacy papers and find the ones called something like map-5, there are some tough questions there if you skim through those papers

Thank you

Reply 33

misslili118

Original post by jjsnyder

here is the working for c, i spent a while looking at the best method to explain it. It is not an easy question, so i apologise if the solution is confusing, let me know if you have any questions :smile:

posted from tsr mobile

thank you omg

Reply 34

misslili118

Original post by hjyu1

i couldnt get the last part, it just destroyed my brain and i think my working for bi) is right not too sure tbf

thank you so much

Reply 35

TheLifelessRobot

Original post by jjsnyder

Posted from TSR Mobile

I converted the co-ordinates of P, N and Q into Cartesian and used length of lines for PN, NQ and QP to find out the angle using cosine rule. Would I still get the marks?

Reply 36

Hjyu1

Does anyone mind explaining why we have to get rid of the minus sign in part biii)

Reply 37

jjsnyder

Original post by TheLifelessRobot

I converted the co-ordinates of P, N and Q into Cartesian and used length of lines for PN, NQ and QP to find out the angle using cosine rule. Would I still get the marks?

Yeah that's fine, it would still get you all the marks and would be included in the more detailed mark scheme that examiners get, but it would take longer of course.

Posted from TSR Mobile

Reply 38

jjsnyder

Original post by Hjyu1

Does anyone mind explaining why we have to get rid of the minus sign in part biii)

What did you get for the value of 6ii? :smile:

Posted from TSR Mobile

Reply 39

TheLifelessRobot

Original post by Hjyu1

Does anyone mind explaining why we have to get rid of the minus sign in part biii)

The limits used for part bii are not the limits that are used to evaluate biii. The limits for part bii actually switch to calculate biii. They should be 0 (upper) and 1 (lower) instead of 1 (upper) and 0 (lower). This is because of the substitution; when you change the limits for the substitution using y=1/x, you calculate y=1/infinity = 0 for the upper and y=1/1 = 1 for the lower. If you calculate the integral again using the limits 0, 1 instead of 1, 0 the sign changes and becomes positive. You'd get 0 - -1/2 = 1/2 instead of -1/2 - 0 = -1/2 for the definite integral.