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# Stuck on a 3D trig question! watch

1. Hi,

Can someone please help with this question? I have got part A correct, but B and C are wrong.

A: 11.5
B: 20.4°
C: 22.9°

Thanks!

2. (Original post by RuWill2001)
...
3. (Original post by RuWill2001)
Here, sorry, I didn't even realise! http://prntscr.com/dsn2zb
I've only glanced at it but M is in the wrong place on your diagram. M is the midpoint of AD.
4. (Original post by Mr M)
I've only glanced at it but M is in the wrong place on your diagram. M is the midpoint of AD.
Ahh, thanks! I will try it now, thx!
5. sorry. I'm usually good at this stuff but i don't get the question.
it would be a help if theimage was rotated
6. (Original post by HS2030)
sorry. I'm usually good at this stuff but i don't get the question.
it would be a help if theimage was rotated
There's a rotated version in post 2.
7. for question b i got the same answer as you so im not sure what i did wrong

but for c, firstly m is the midpoint of ad not dc
to work out the angle first we have to work out the length of at least two sides of the triangle agc
so we have one given lenghth, gc which is 4cm, but we need to we need to work out the length of cm
the triangle cmd makes a right angle which we can use to work out cm

once youve worked that you you can use trigonmetry to work out the angle cmg
8. Thanks all, I have got it now!

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