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Math III Videos 103 videos

Unit Rate
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Approximately 874 people per day wonder what a unit rate is. If you're one of them, check out our video on unit rates and how to use them. (We just...

Solving Proportions Using Cross Products
6802 Views

This video covers how to use cross products to solve for a missing number in a proportion by setting that proportion with a variable over the produ...

GED Math 2.4 Rational Numbers
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GED Math 2.4 Rational Numbers. Lucius's favorite restaurant is how many km from his home?

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SAT Math 5.2 Geometry and Measurement 253 Views


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Description:

SAT Math 5.2 Geometry and Measurement

Language:
English Language

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.

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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