You are Here: Home >< Maths

# Integrating parametric equations

Announcements Posted on
Why bother with a post grad? Are they even worth it? Have your say! 26-10-2016
1. I'm stuck on a question from the C4 book (chapter 6, Mixed Exercises 15 (d)).

I understand finding the area of the whole triangle, but not how to find the area of A1. Why is the curve 4sinθ(-5sinθ)? I know how to go from there, but not how they got that equation.

Thanks guys!
2. (Original post by кяя)
I understand finding the area of the whole triangle, but not how to find the area of A1. Why is the curve 4sinθ(-5sinθ)? I know how to go from there, but not how they got that equation.

Thanks guys!

3. (Original post by кяя)
...
As an alternative to the above (I prefer this once since you get used to the idea of substitutions being scalings and this will help once you do multivariate calculus and need to deal with Jacobians, but I digress):

You know the area under a curve is given in cartesian co-ordinates as , yes? But at the same time you can think of since they 's kind of cancel.

Let's go ahead and re-write this now:

Now you know that and and but then the negative sign means you flip them, so you're left with:

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: April 12, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams