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Geometry and Measurement Videos 88 videos
SAT Math 1.1 Geometry and Measurement. What is the circumference of the circle?
SAT Math: Geometry and Measurement Drill 1, Problem 2. If A = (0, 4), B = (-3, 2), and C = (1, 0), which point is in the interior of angle ABC?
SAT Math 2.3 Geometry and Measurement. Find the length of AB.
SAT Math 1.3 Geometry and Measurement 231 Views
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Description:
SAT Math 1.3 Geometry and Measurement. Find the length of CE.
- Triangles / 30°-60°-90° Triangles
- Product Type / SAT Math
- Geometry / Similarity, right triangles, trigonometry, and dimensions
- Geometry / Define trigonometric ratios and solve problems involving right triangles
- Similarity, Right Triangles, and Trigonometry / Define trigonometric ratios and solve right triangle problems
- Problem Solving and Data Analysis / Key features of graphs
Transcript
- 00:03
Here’s your shmoop du jour, brought to you by the length of a line.
- 00:07
Although…we hear it’s been using supplements.
- 00:10
Find the length of CE.
- 00:13
Here's a little picture and we're looking for the length of this line right here.
- 00:18
And here are the potential answers...
Full Transcript
- 00:22
We know right off the bat, for example, that triangle CDE is a 30-60-90 triangle.
- 00:37
…and we remember that the sides of a 30-60-90
- 00:40
triangle always have a ratio of x to x square root of 3 to 2x.
- 00:46
It’s pretty obvious that DE is the longer of the two legs…
- 00:50
…and even if we weren’t sure by eyeballing it, we know it has to be the side across from the 60…
- 00:55
…so we can use that information to solve for CE, the hypotenuse.
- 01:00
5 equals x square root of 3.
- 01:03
We want to get x alone…
- 01:06
…so we divide both sides by square root of 3…
- 01:09
…and x equals 5 over the square root of 3.
- 01:13
Our hypotenuse has to be 2x…so multiply that whole thing by 2 and we wind up with
- 01:18
10 over the square root of 3. Of course, we have this thing about leaving
- 01:23
square roots in the denominator… …so multiply both the top and bottom by
- 01:26
square root of 3 and we have 10 square root of 3 all over 3…
- 01:31
…which is answer B.
- 01:33
We didn’t even need triangle ABC. Who knows why they threw that in here.
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