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ACT Math: Plane Geometry Drill 3, Problem 3. What is the measure of angle ABC?
SAT Math 11.1 Geometry and Measurement. If y equals 117°, what is the measure of x?
ACT Math 3.3 Plane Geometry 487 Views
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Description:
ACT Math: Plane Geometry Drill 3, Problem 3. What is the measure of angle ABC?
Transcript
- 00:02
For a good time solve this shmoopy question...
- 00:04
What is the measure of angle ABC if line
- 00:08
AC measures 2pi, B is the center, and line BC measures 4?
- 00:14
Here are the potential answers...
- 00:18
Here's angle ABC. This arc AC
Full Transcript
- 00:22
is 2pi and line BC right here
- 00:25
is 4. We also know that circle problems are gonna test us on
- 00:29
two basic formula usually. Area
- 00:32
which is pi r squared and circumference which is 2
- 00:36
pi r. We've been told that line BC is a radius
- 00:40
so let's plug it in to solve for circumferance
- 00:43
since line BC is 4 is for we know that 2
- 00:46
pi 4 is just 8pi. They give us
- 00:50
that this arc is 2 pi so what's 2
- 00:54
pi over 8pi? Yeah, it's 1/4 and
- 00:57
all the way around the clock is 360 degrees. 1/4 of the way around the clock
- 01:02
is from midnight to 3
- 01:04
recognize anything special about this little angle here?
- 01:07
Yeah. It's right!
- 01:10
This right. Yeah ninety degrees. It's E.
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