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Math 4: Angles as Additives 4 Views
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Description:
Did you know that angles have an additive property? Oh, you did? You have that fact graffitied on your bedroom wall? Well, okay then. No need to watch this video, we guess.
Transcript
- 00:13
So anytime you need to take the measurement of an angle, you know that a protractor is [Guy holding a protractor]
- 00:18
the best tool for the job, right?
- 00:19
….Right…?
- 00:20
…Why on earth are you holding a blowtorch? [Guy swaps the protractor for a blowtorch]
- 00:21
How does that seem like a good idea?
Full Transcript
- 00:24
Seriously…okay, nope. [Guy sets fire to the angle]
- 00:26
Never mind.
- 00:27
Moving on.
- 00:28
But what if you didn’t have a protractor?
- 00:29
Could you still figure out the measure of the angle? [Girl gets her protractor taken away]
- 00:32
Turns out, you can!
- 00:33
How?
- 00:34
Ohhhhhh, put down the blow torch. [Man comes in holding two blow torches]
- 00:35
It has nothing to do with blowtorches.
- 00:37
Thank you.
- 00:38
So how do we do it? [Man with blowtorches and flames in the background]
- 00:39
Well, turns out, angles are additive, which means, “the sum of the parts of an angle
- 00:43
are equal to the whole of the angle.” [Dino pointing to a blackboard]
- 00:46
Which sounds more confusing than it actually is.
- 00:48
So let’s see what we’re working with here. [Hippy in a supermarket]
- 00:51
Suppose two angles are at a dance, eyeing one another from across the room. [Two angles on the dance floor]
- 00:55
Through some stroke of luck, they end up next to one another as the music plays…
- 00:59
You can see the measurements of each angle – 40-degrees and 50-degrees. [Angles move closer together]
- 01:04
The “additive” property of angles means that if you add those two measurements together…
- 01:08
You’ll get the measurement of the larger angle they make. [The two angles combine to make 90 degrees]
- 01:11
The additive property of angles is handy to know in a pinch.
- 01:14
It means that, with just a couple of clues, you can find a missing angle measurement. [Coop pointing at a blackboard]
- 01:18
So if you have the measurement of the whole, large angle, and only one of the smaller angles,
- 01:23
can you figure out the other one?
- 01:25
Youuuuu betch--PUT DOWN THE BLOWTORCH. [Guy sets fire to the angle again]
- 01:28
Using the information you have, you can subtract 33-degrees from the whole angle measurement
- 01:32
of 75-degrees and discover that the missing measurement has to be 42-degrees.
- 01:37
Easy-peasy.
- 01:38
And no terrifying firey tools required. [Flames appear again]
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