Lesson video

Hello, and welcome to today's lesson about bearings, rotating scaling triangles.

For today's lesson, all you need is a pen and paper or something to write on and with.

Please take a moment to clear away any distractions, including turning off any notifications.

Finally, try find a quiet space to work where you won't be disturbed.

When you're ready, let's begin.

Try this.

I don't want to give too much away.

So just pause the video and have a go.

Pause in three, two, one.

Hopefully you've managed to work a few things out.

I'm going to talk you through the things that I worked out.

Bearing of B from A, that's from A and to get to B that is that angle there.

What else can I work out? Can I work out this angle here? I've got those two and they form a triangle.

This must be 180.

Subtract, Why? Because interior angles in a triangle add up to 180.

That means that that is 30.

I can work out the bearing of C from A, which is 100 What other angles could I work out all of the bearings, we've got two North lines a North line is a parallel, that is 70.

And this here, those two must add up to 180.

I can do 180 subtract 70 which gives me 110 and I have found my co interior angle.

Could I work out this angle? I can get the bearing of C from B Sorry, my line going a bit crazy there.

Those what must they add up to? They form their angles around a point.

They must add up to 360.

360 subtract 110 plus 100 which is 150.

I have an angle of 150 here.

The bearing of C from B is 150 I never know of that, then I know that this 150 and this there are core interior.

That must be 30.

Because they must add up to 180.

We can use that and that to find this one they add up to get 80.

360, subtract 80 is 280.

A is on a bearing of 280, From C.

Hopefully you'll managed to work out a few of them.

And don't worry, if you didn't manage to work out more.

We're going to be exploring these skills more on this lesson, you'll get more practise and more chance to show me what you can do.

Find the bearing of B from A.

We're from A.

That means we're at A we're starting off, and we go clockwise.

We want to know what that angle is.

How could we find this angle? That plus that plus that must add up to 180.

Because the sum of the interior angles in a triangle add up to 180.

To find that angle, I can do 180, not 360, subtract 92 plus 38.

That adds up to 130.

Next two plus 100 plus 30, 130.

180 minus 130 equals 50.

That gives me that angle.

How do I find this one? They must add up to 360.

360 Minus that one, minus that one gives me, plus that one sorry, plus that one.

Add them together.

310, 360 minus 310, 50.

And it's just a coincidence, they're both 50.

They're not always both 50.

My bearing of B from here depends on what that angle is, which is 50.

My bearing is zero 50.

Remember, it must have three figures.

I'd like you to try this Your turn, why? Pause the video and have a go.

Pause in three, two, one.

Hopefully, you've worked out this angle 180 subtract 95 Plus 35.

And you got an answer of 50 for that.

Now that's 255.

And that's 50.

I can work out that because they add up to 360.

I'm going to sneakily use this diagram here, 'cause that was 260.

And that was 50.

That is five less than 260.

And that's the 50%.

That is going to be five mile.

It's going to be 55.

I use that connection between these two questions to help me do the arithmetic.

Well done if you manage to spot that, find the bearing of C from B.

Where is that on our diagram, from B staring North, going clockwise to C.

That's that angle there, at the moment I don't have enough information to work that out, I'm going to have to work out something else first.

And I'm going to work out this one because I've got two parallel North lines.

I can use co interior angles.

This plus this must be 180 because they are co interior.

We have a full turn, angles around a full turn, add up to 360.

And if I work that out, that should give me 138.

Our bearing is 138.

Your turn, pause the video and have a go pause in three, two, one.

Welcome back.

Hopefully you used co interior angles then we'll start up to 180 to get that is 125.

You should have done and that should give you an answer of 140.

Our bearing is 140 degrees, well done if you've got that correct And last one, find the bearing of A from C.

We're from C, that means we're here.

We want to find, this angle there.

We can't quite at the moment, but I can find out this angle there using the fact that the North lines are parallel.

Those two are co interior.

That means that, that and that add up to 180.

That should give me 12.

If that's 12 and that's 38, we can do 360 minus those two and that will give us this angle here.

They add up to 50.

360 minus 50 is 310.

My bearing of A from C is 310.

Your turn.

I'll let you have a go at this one.

Pause the video in three, two, one.

And welcome back.

Hopefully you worked out this angle here, using co interior angles.

That was 40.

If you've got that 40 and that's 35, plus that should add up to 360.

360 subtract them too will give us our missing angle and which is 75, 360 minus 75, which is 285.

It's got a bearing of 285.

I'd like you to have a go at the independent task.

Pause the video to complete your task, resume once you're finished.

And here are my answers.

I'd like to pause the video and mark your work.

Pause in three, two, one.

It's time for the explore tasks.

I'd like you to pause the video, complete your task resume once you're finished.

See what patterns you noticed.

Here are my answers for the Explore task.

We have quite an interesting pattern here.

Look, 70, 80, 90.

150,160,170.

280, 290, 300.

why is that happening? I want you to have a think about that.

And I want you to try and explain to yourself or someone else why this pattern is happening.

And that is it for today's lesson.

If you'd like to please ask your parent or carer to share your work on Twitter tagging @OakNational and #LearnwithOak, thank you very much for taking part and thank you very much for all your hard work.

I will see you next time.

Thank you.