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Angles in Polygons Videos 4 videos
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ACT Math: Plane Geometry Drill 4, Problem 3. What is the measure of each angle in the figure?
SAT Math 6.4 Geometry and Measurement 287 Views
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Description:
SAT Math 6.4 Geometry and Measurement
Transcript
- 00:03
Here’s your shmoop du jour, brought to you by parallel lines.
- 00:07
Some are more delicious than others.
- 00:11
ABCD is a parallelogram. If angle B is equal to 30°, what is the measure of angle ACB?
- 00:20
Here are the potential answers...
- 00:22
Okay, what do we know about parallelograms…?
Full Transcript
- 00:25
They look like rectangles that an elephant sat on…
- 00:27
Well, we know that opposite sides are… parallel, obviously.
- 00:31
We also know that opposite angles are congruent.
- 00:35
So…because we’re told that angle B is 30 degrees…
- 00:38
…we know that angle D is 30 degrees as well. Great.
- 00:41
We’re dealing with a four-sided polygon, so we must have 360 total degrees.
- 00:46
If 30 and 30…or 60…are already accounted for…
- 00:48
…then the two remaining angles must make up the difference.
- 00:51
So just subtract those 60 degrees from the 360 and we get 300…
- 00:55
and once again we have opposite angles that must be equal.
- 00:59
So…300 divided by 2 is 150.
- 01:03
Line AC is bisecting that angle…leaving us with an angle of 75 degrees.
- 01:09
Answer E.
- 01:10
As in, “Elephant.”
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