You are Here: Home >< GCSEs

# Trigonometry

Announcements Posted on
TSR's new app is coming! Sign up here to try it first >> 17-10-2016
1. Find the exact area of the triangle with side lengths of 4cm, 5cm and 6cm.
I get the area to be 9.9cm^2.
2. Anyone?
3. (Original post by Ano9901whichone)
Anyone?
No angles?
4. http://www.mathopenref.com/heronsformula.html

9.9 is right but it isn't exact
5. I was going to suggest that but Heron's doesn't involve trigonometry and he wants the "exact" answer, so 9.9 is not correct but rather rounded.
6. https://www.wolframalpha.com/input/?...F2-5)(15%2F2-6))

1. Use Heron's formula
2. Simplify
7. (Original post by Ano9901whichone)
Find the exact area of the triangle with side lengths of 4cm, 5cm and 6cm.
I get the area to be 9.9cm^2.
Show your working, you don't necessarily need to use Heron's for this. I got
8. Is Heron's formula GCSE?
I've certainly never came across it, in either GCSE or A Level and had never heard of it before this thread.
Did this by getting the cosine of an angle from the cosine rule, then working out sine of the same angle using SOHCAHTOA, and finally subbing the sine of the angle into the formula 1/2 ab sin C
9. (Original post by AlexS101)
Is Heron's formula GCSE?
I've certainly never came across it, in either GCSE or A Level and had never heard of it before this thread.
Did this by getting the cosine of an angle from the cosine rule, then working out sine of the same angle using SOHCAHTOA, and finally subbing the sine of the angle into the formula 1/2 ab sin C
No it's not. I just noticed this is in the GCSE section. Yes what you said is the best way for a GCSE student (I just couldn't be bothered to use the cosine rule and then the area formula)

## 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: July 29, 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

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

## Study tools

### Essay expert

Learn to write like a pro with our ultimate essay guide.

See where you can apply with our uni match tool

### Make study resources

Create all the resources you need to get the grades.

### Create your own Study Plan

Organise all your homework and exams so you never miss another deadline.

### Resources by subject

From flashcards to mind maps; there's everything you need for all of your GCSE subjects.

### Find past papers

100s of GCSE past papers for all your subjects at your fingertips.