Comments for The Sydenham High School Mathematics Department Blog

Comment on Mr Brewin’s Year 9 – Sine and Cosine Rules by Mr Brewin

Mr Brewin — Wed, 10 Mar 2010 22:03:07 +0000

Come and see me tomorrow Aalia if you can.

Comment on Mr Brewin’s Year 9 – Sine and Cosine Rules by Mrs Tibble

Mrs Tibble — Wed, 10 Mar 2010 21:18:30 +0000

Aalia, I don’t know which book you are using, but if it’s Sine and Cosine rules then the triangles won’t be right-angled so you shouldn’t be using Pythagoras.
Look at your lesson notes – there’s an extra term in the cosine rule that you mustn’t ignore.
They don’t tell you the angle because that is what the question wants you to find. The cos of an obtuse angle is negative so it’s OK to get a negative number. You shouldn’t, however, be trying to square-root it!
Have another go and bring your attempt to someone in the department for help.
JT

Comment on Mrs Tibble’s Year 10 by Mrs Tibble

Mrs Tibble — Wed, 10 Mar 2010 21:12:06 +0000

Hi Asha,
Hope you had success after we redrew it on plain paper!!
See you tomorrow,
JT

Comment on Mr Brewin’s Year 9 – Sine and Cosine Rules by aalia

aalia — Wed, 10 Mar 2010 18:26:31 +0000

Mr brewin, for questions e on both, they dont tell you the angle, and also for question 2. When using cosine, do you have to change the a^2=b^2+c^2 when the hyp has all ready been shown? its really confusing and i dont understand them, and on a question i got a negative answer and you cannot find the square root!!

Comment on Mrs Tibble’s Year 10 by Asha Williams

Asha Williams — Wed, 10 Mar 2010 16:34:31 +0000

Hello Mrs Tibble I really don’t understand the maths i tried to draw the cube and i drew a cube but not with the correct coordinates because i couldn’t figure out the paper, that was Q.4. Then i tried to go back up and do question 3 but i wasn’t sure wheather to draw it. And now i feel lost and confused. Please help!

Comment on Mrs Tibble’s Year 11 by Mrs Tibble

Mrs Tibble — Mon, 08 Mar 2010 21:19:25 +0000

Hi Charlie,
That doesn’t matter. Just make sure you take note of those signs when adding or subtracting.
JT

Comment on Mrs Tibble’s Year 11 by Charlie

Charlie — Mon, 08 Mar 2010 20:40:52 +0000

mrs, im abit baffelled bout how to do number 7 in the homework… coz both x and y have positive and negative values….

Comment on Mrs Tibble’s Year 7 by Mrs Tibble

Mrs Tibble — Thu, 04 Mar 2010 19:18:13 +0000

Bella,
Sorry – just realised I was looking at the red shape, not the orange! 4a isn’t a rotation as it doesn’t turn: it’s a translation.

Comment on Mrs Tibble’s Year 7 by Mrs Tibble

Mrs Tibble — Thu, 04 Mar 2010 19:14:52 +0000

Hi Bella,
Use some tracing-type paper to help you. Copy the diagram into your book. Trace the pink shape then pin the tracing paper down somewhere with your pencil and rotate the paper to see if the shape then lies on top of the orange one. If it doesn’t, pin the paper down somewhere else. Keep trying till you find the right point for the centre of the rotation.
JT

Comment on Mrs Tibble’s Year 7 by Bella Hudd

Bella Hudd — Thu, 04 Mar 2010 17:48:50 +0000

HI I’m stuck on question 4a on the homework.