This discussion is now closed.

Check out other Related discussions

- Official Year 11 Chat Thread 2024-25
- 2025 Westminster 16+
- Further Maths more enjoyable than Maths (at level 2)
- GCSE Mathematics Study Group 2023-2024
- i got 11 9s and an A - sharing my resources
- From foundation to higher
- NOTES FOR GCSE URGENT + gimme some tips for grade 9 pls
- A level Mathematics Edexcel Help
- How to get a 9 in gcse maths
- maths degree - help - about maths degree
- maths a level
- mature student in need of some advice.
- Maths gcse
- gcse maths tips pls
- GCSE maths doubt
- Any good revision resources/ websites for GCSE?
- Maths GCSE/A level
- Maths revision GCSE
- PLEASE HELP. Westminster 16+ entrance exam
- OCR GCSE Maths Shadow papers

Hey everyone,

Got this question which shouldn't be troubling me but I can't get my head around it:

"Here is the net of a cone

The net is a sector of a circle, centre 'O', and radius 15 cm.

Reflex angle AOB = 216 degrees.

The net makes a cone of slant height 15 cm.

Work out the vertical height of the cone."

I hope that's clear enough for everyone, sorry about the quality (tried to do it quickly in paint).

I've got an idea of the formulas to use, but I'm going to keep my mouth shut to see how close I was to the proper answer.

Any help will be much appreciated. Thanks a lot.

Got this question which shouldn't be troubling me but I can't get my head around it:

"Here is the net of a cone

The net is a sector of a circle, centre 'O', and radius 15 cm.

Reflex angle AOB = 216 degrees.

The net makes a cone of slant height 15 cm.

Work out the vertical height of the cone."

I hope that's clear enough for everyone, sorry about the quality (tried to do it quickly in paint).

I've got an idea of the formulas to use, but I'm going to keep my mouth shut to see how close I was to the proper answer.

Any help will be much appreciated. Thanks a lot.

You find the circumference of the whole circle.

pi * diameter = 30π

You then find the circumference of the circle that will make up the base of the cone which is: 30π * (216/360)

You then work out the radius of this circle

which is: (30π * (216/360))/2π

You then use Pythagoras' rule to find the vertical height.

a² + b² = c²

which is c²/a² = b²

so ((30π * (216/360))/2π² / 15² = vertical height

I dont have a calculator but that should give you the correct answer

pi * diameter = 30π

You then find the circumference of the circle that will make up the base of the cone which is: 30π * (216/360)

You then work out the radius of this circle

which is: (30π * (216/360))/2π

You then use Pythagoras' rule to find the vertical height.

a² + b² = c²

which is c²/a² = b²

so ((30π * (216/360))/2π² / 15² = vertical height

I dont have a calculator but that should give you the correct answer

It will actually be c2-a2= b2 not c2/a2=b2 but everything else is correct!

- Official Year 11 Chat Thread 2024-25
- 2025 Westminster 16+
- Further Maths more enjoyable than Maths (at level 2)
- GCSE Mathematics Study Group 2023-2024
- i got 11 9s and an A - sharing my resources
- From foundation to higher
- NOTES FOR GCSE URGENT + gimme some tips for grade 9 pls
- A level Mathematics Edexcel Help
- How to get a 9 in gcse maths
- maths degree - help - about maths degree
- maths a level
- mature student in need of some advice.
- Maths gcse
- gcse maths tips pls
- GCSE maths doubt
- Any good revision resources/ websites for GCSE?
- Maths GCSE/A level
- Maths revision GCSE
- PLEASE HELP. Westminster 16+ entrance exam
- OCR GCSE Maths Shadow papers

Latest

Trending

Last reply 2 weeks ago

i got grade 9s in all my sciences and maths.ask me any questions you have.GCSEs

12

17