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Parallel and Perpendicular Lines Videos 23 videos
This video explores parallel lines and transversals: how to identify them both on a math test and in real life urban planning. What do the consecut...
To prove lines are parallel, you need a third line. We at Shmoop (and the rest of the world) call it a transversal.
SAT Math 5.2 Geometry and Measurement 253 Views
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Description:
SAT Math 5.2 Geometry and Measurement
Transcript
- 00:02
Here’s your shmoop du jour, brought to you by interlocking circles.
- 00:13
How many tangent lines can be drawn to exactly two circles in the picture below?
- 00:18
Here are the potential answers...
- 00:22
First up, let’s make sure we all know what a tangent is.
- 00:26
And no, it's not a funky kind of orange.
Full Transcript
- 00:28
The one that connects at an arc or circle at exactly one point is a tangent.
- 00:38
The easiest way to solve this problem is to start by imagining that one of these circles isn’t even there.
- 00:45
Poof, it’s gone.
- 00:46
There are all sorts of tangent lines we can draw to one of these circles…
- 00:49
…but only two will hit both circles at exactly one point.
- 00:54
Now if we do the same with a different pair of circles, we get the same result.
- 00:59
Same deal with the final pair.
- 01:01
So…looks like we get 2 tangents times 3 possible pairings…
- 01:05
…for a grand total of 6 tangent lines.
- 01:07
And boom, we’ve got our answer – option D.
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