You are Here: Home >< Maths

1. I have no clue what to do with this question. Any hints?

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36cm^2, find the value of r.

I know that the perimeter is therefore 24cm. What should I be doing now? :/

Posted from TSR Mobile
2. (Original post by JodieW)
I have no clue what to do with this question. Any hints?

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36cm^2, find the value of r.

I know that the perimeter is therefore 24cm. What should I be doing now? :/

Posted from TSR Mobile
What's the arc length of the sector in terms of r?

Then the perimeter of the sector is the length of the two radii (2r) plus the length of the arc and this sum is equal to 24.
3. (Original post by JodieW)
I have no clue what to do with this question. Any hints?

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36cm^2, find the value of r.

I know that the perimeter is therefore 24cm. What should I be doing now? :/

Posted from TSR Mobile
You can find the arc length and of course the radii in terms of r. The perimeter of the sector will be made up of three sides.
4. (Original post by JodieW)
I have no clue what to do with this question. Any hints?

A sector of a circle of radius r cm contains an angle of 1.2 radians. Given that the sector has the same perimeter as a square of area 36cm^2, find the value of r.

I know that the perimeter is therefore 24cm. What should I be doing now? :/

Posted from TSR Mobile
so for the sector you have a pizza slice with two sides as radii of the circle and the other being the arc formed through and angle of 1.2 rads

you know that the angle times the radius is the arc length

so you get 24=r+r+1.2r which you can solve
5. I got r=7.5 not sure if its right?

2r+1.2r=24
3.2r=24
r=7.5

7.5x1.2=9 for the length of arc

7.5+7.5+9=24 the perimeter.
6. (Original post by florencechu)
I got r=7.5 not sure if its right?

2r+1.2r=24
3.2r=24
r=7.5

7.5x1.2=9 for the length of arc

7.5+7.5+9=24 the perimeter.
Correct
7. (Original post by florencechu)
I got r=7.5 not sure if its right?

2r+1.2r=24
3.2r=24
r=7.5

7.5x1.2=9 for the length of arc

7.5+7.5+9=24 the perimeter.
It's against the rules to post full solutions.

In future, if you want clarification of a question that isn't yours, please wait until the OP has done the question themselves.
8. (Original post by notnek)
It's against the rules to post full solutions.

In future, if you want clarification of a question that isn't yours, please wait until the OP has done the question themselves.
Oops my bad I didnt know that, sorry!
9. (Original post by notnek)
What's the arc length of the sector in terms of r?

Then the perimeter of the sector is the length of the two radii (2r) plus the length of the arc and this sum is equal to 24.

Hi, I was attempting the question myself, how do you get 24 as the perimeter? I thought it was 36? :O
10. (Original post by IgorYakov)
Hi, I was attempting the question myself, how do you get 24 as the perimeter? I thought it was 36? :O
The area is 36 cm^2 and it is a square.
11. (Original post by IgorYakov)
Hi, I was attempting the question myself, how do you get 24 as the perimeter? I thought it was 36? :O
The area of the square is 36 which means that the side length is 6.
12. (Original post by notnek)
The area of the square is 36 which means that the side length is 6.

Oh, damn yeah, can't believe I forgot that. Thanks!

### Related university courses

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:
Updated: March 31, 2013
Today on TSR

### He broke up with me because of long distance

Now I'm moving to his city

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams