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New Maths GCSE 9-1 Sample Question Confused?!

I was looking through my revision guide and this question looked easy until i tried it:
"A ship sails 12km on a bearing of 050°, then 20km on a bearing of 100°. It then sails directly back to its starting position. CALCULATE this distance to 1 d.p."

Anyone know how to do this without any drawings but only using the sine/cosine rule?

Reply 1

gdunne42

Original post by NothingButWaleed

It's a cosine rule question
Sketch the information and use your sketch and knowledge of bearing/parallel line angle facts to work out the angle between the 12 and 20 km lines.

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Reply 2

NothingButWaleed

Original post by gdunne42

It's a cosine rule question
Sketch the information and use your sketch and knowledge of bearing/parallel line angle facts to work out the angle between the 12 and 20 km lines.

Posted from TSR Mobile

Wait I dont fully follow...
Could you give me an example please?
Thanks!

Reply 3

gdunne42

Original post by NothingButWaleed

Wait I dont fully follow...
Could you give me an example please?
Thanks!

Reply 4

NothingButWaleed

Original post by gdunne42

I figured out how to work out the right question mark but no hope for the left one...
How do you work out the "?" angle?

Reply 5

gdunne42

Original post by NothingButWaleed

I figured out how to work out the right question mark but no hope for the left one...
How do you work out the "?" angle?

You need to revise parallel line angle facts.
Alternate angles are equal

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Reply 6

NothingButWaleed

Original post by gdunne42

You need to revise parallel line angle facts.
Alternate angles are equal

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Yeah I know those rules but if i used them the interior angles is 210 degrees which it cant be as angles add up to 180 in a triangle thats why im confused!