The Student Room Group

Intergration question

Hi guys im not sure how to approach question 2c.

i have attempted the question but i got the wrong answer, i tried to intergrate the equation of the straight line with the parameters substituted in with respect to t between the two points of intersection.

Any hints would be appreciated. Not sure if any can understand what i tried to do.

Thanks in advance. Pictures down below
Reply 1
image.jpg
Attachment not found
Attachment not found
Reply 2
I would do this in three parts. One for the area under the top branch, one for the area above the bottom branch, and then the triangles to make the whole shape.

Note that the question is asking for an area in the xy-plane, so you will be integrating y with respect to x or x with respect to y (and you do change them to t, but not like you have done).
Original post by Shaanv

Not sure if any can understand what i tried to do.

Thanks in advance. Pictures down below


Have to say, I'm not entirely clear what you've tried to do with your integration. Perhaps it's this:

I can see one method whereby you can do it with a single integral. Integrate with respect to y (not x), x-value-of-line minus x-value-of curve, between the y coordinates of Q and P.

Failing that, the method suggested by ThomH97 of breaking the area up into various pieces would work. I would mark the various areas on the diagram. as they're not immediately obvious.
Reply 4
Sorry i still dont really understand what u mean.

For area under the top branch would i get it from doing the following
image.jpg
Reply 5
Original post by Shaanv
Sorry i still dont really understand what u mean.

For area under the top branch would i get it from doing the following
image.jpg


Yup, bear in mind that gives you an extra triangular region between P, (12,0) and (4,0) to the right of the orange region.
Here's the diagram with some points marked, to aid clarity of expression.
image.jpg
Reply 7
image.jpgU guys were absolutely write thanks for ur help.

I think what got me was that initially i couldnt see the triangle to help with the area under the line.

Thanks again
Reply 8
Original post by ghostwalker
Have to say, I'm not entirely clear what you've tried to do with your integration. Perhaps it's this:

I can see one method whereby you can do it with a single integral. Integrate with respect to y (not x), x-value-of-line minus x-value-of curve, between the y coordinates of Q and P.

Failing that, the method suggested by ThomH97 of breaking the area up into various pieces would work. I would mark the various areas on the diagram. as they're not immediately obvious.


Honestly i didnt have a clue where to start and i wanted to try and do it in one integral to no avail.
Thought id have a try before i came to ask.
Reply 9
Original post by Shaanv
image.jpgU guys were absolutely write thanks for ur help.

I think what got me was that initially i couldnt see the triangle to help with the area under the line.

Thanks again


You're welcome :smile:

It is best to try to break things up into bits you know how to do like ghostwalker did, and be on the lookout for triangles (sometimes rectangles) that you can use to make things easier.
Reply 10
Original post by ThomH97
You're welcome :smile:

It is best to try to break things up into bits you know how to do like ghostwalker did, and be on the lookout for triangles (sometimes rectangles) that you can use to make things easier.


Much appreciated got another 30 questions similar to this then im done with my c4 exercises. Then gonna plough through m2

Quick Reply

Latest