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Sine is the opposite over the hypotenuse; cosine is the adjacent over the hypotenuse; and tangent is the opposite side over the adjacent side....
FYI: cats don't like to get wet. Okay, so that fact won't be relevant every time you solve trig equations, but it happens to be this time.
SAT Math 4.2 Geometry and Measurement 278 Views
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Description:
SAT Math 4.2 Geometry and Measurement
- Geometry and Measurement / Transformations
- Product Type / SAT Math
- Geometry / Experiment with transformations in the plane
- Geometry / Understand congruence in terms of rigid motions
- Geometry / Understand similarity in terms of similarity transformations
- Congruence / Experiment with transformations in the plane
- Congruence / Understand congruence in terms of rigid motion
- Similarity, Right Triangles, and Trigonometry / Understand similarity in terms of transformations
- Additional Topics in Math / Right triangle problems (word problems)
Transcript
- 00:02
Here’s your shmoop du jour, brought to you by rotating triangles.
- 00:10
Triangle ABC is rotated 90° counterclockwise about the origin, then reflected over the y axis.
- 00:17
What are the new coordinates of C?
- 00:19
Here are the potential answers...
- 00:24
Who knows why we’re rotating and reflecting this triangle…
Full Transcript
- 00:27
…maybe it was getting stir crazy and wanted a change of scenery.
- 00:30
Whatever the reason, this problem tells us that we must first rotate the sucker 90 degrees about the origin…
- 00:36
…and then reflect it across the y axis.
- 00:40
When we rotate the triangle about the origin,
- 00:42
that means that we have to picture the entire thing on a hinge…
- 00:46
…and that hinge is at zero, zero.
- 00:48
…we just have to imagine that pivot point, and swing the whole thing around from there.
- 00:53
When we do that, our triangle ends up here…
- 00:55
…with point C at (-2, -1).
- 00:59
And now the easy part. When we reflect a shape across an axis, all we do is flip it.
- 01:04
We can see that point C now sits at (2, -1)…
- 01:07
…which is choice E, our final answer.
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