ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
SAT Math Videos 171 videos
SAT Math 1.1 Statistics and Probability. In which of the following data sets are the arithmetic mean and the median equal?
SAT Math: Statistics and Probability Drill 1, Problem 2. If the four largest numbers in the set were doubled, what would happen to the median...
SAT Math 1.3 Statistics and Probability. Approximately what is the probability that they will be placed in alphabetical order?
SAT Math 4.2 Geometry and Measurement 294 Views
Share It!
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.
Related Videos
SAT Math 2.1 Geometry and Measurement. What is the measure of angle z in terms of x and y?
In 2014, the unemployment rate of one county in California was 7%. In another county, the unemployment rate was 11%. Which of the following express...
Angela is making cookies for a bake sale. She expects each batch of her cookies to sell for $40. It costs her $10 to make one batch of cookies, and...