Help with forces in action question

OCR a level

Hey all. I’m normally alright at doing these triangle of forces questions but this one has stumped me.

The question in the book (image below) does it one way which I don’t like so I tried to draw the diagram. Where am I cocking up?

Thanks

(Doesn’t allow me to upload. Hope you’re okay with links - https://imgur.com/a/15ikFct)

Reply 1

mqb2766

21

Original post by Olly5847558

OCR a level

Hey all. I’m normally alright at doing these triangle of forces questions but this one has stumped me.

The question in the book (image below) does it one way which I don’t like so I tried to draw the diagram. Where am I cocking up?

Thanks

(Doesn’t allow me to upload. Hope you’re okay with links - https://imgur.com/a/15ikFct)

your triangle isnt right angled and it would be more obvious to sketch the 25 degree angles a bit smaller as its isosceles 25-25-130. The simplest way is pretty much as the book does so perpendicular bisect of the 120N side to create two identical right triangles, then Tcos(25)=60, though you could also do the sin rule on the original isosceles triangle.

(edited 3 months ago)

Reply 2

Olly5847558

OP

2

Original post by mqb2766

your triangle isnt right angled and it would be more obvious to sketch the 25 degree angles a bit smaller as its isosceles 25-25-130. The simplest way is pretty much as the book does so perpendicular bisect of the 120N side to create two identical right triangles, then Tcos(25)=60, though you could also do the sin rule on the original isosceles triangle.

Managed to figure it out. Thanks though! I was being a stupid idiot thinking I could use SOHCAHTOA on a non right angled triangle! If anyone remotely cares here's how I did it: https://imgur.com/a/ujqB59I

Original post by Olly5847558

OCR a level

Hey all. I’m normally alright at doing these triangle of forces questions but this one has stumped me.

The question in the book (image below) does it one way which I don’t like so I tried to draw the diagram. ....