Name: Using similarity to estimate ratio between side lengths
Uploaded: 2020-04-23T03:33:23.000Z
Duration: 4 min 35 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

- [Instructor] So we've been given some information

And then they say, "Use one of the triangles,"

The ratio's the length of segment PN divided

So they want us to figure out the ratio of PN over MN.

So pause this video and see if you can figure this out.

All right, now let's work through this together.

Now, given that they want us to figure out this ratio

the third angle as well, because the third angle's

completely determined by what the other two angles are.

this doesn't have a 35 degree angle, it has a 90.

But triangle two here has a 35 degree angle,

has a 90 degree angle and has a 55 degree angle.

that this too has a measure of 55 degrees.

And so given that all of our angle measures are

we know that these two are similar triangles.

And so the ratios between corresponding sides are going

We could either take the ratio across triangles.

And then MN, that's this that I'm coloring

And so opposite the 55 degree angle would be

the ratio of the red side, the length of the red side

over the length of the blue side is going

regardless of which triangle you look at.

So if you take the side that's opposite 35 degrees,

Now to be very clear, it doesn't mean that somehow

We would only be able to make that conclusion

But with similarity, we know that the ratios,

to the blue side on each of those triangles,

which of these choices get close to that?

And so we are going to rule this choice out.

And so we have to think between these two choices.

actually just try to start dividing it by hand.

Subtitles ListPlay Video

Using similarity to estimate ratio between side lengths

assume

equivalent

figure

determine