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PSAT 1.25 Math Diagnostic 190 Views
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Description:
PSAT 1.25 Math Diagnostic. What is the area of the shaded sector in square cm?
More Video DetailsTranscript
- 00:00
Thank you We sneak and here's your smoke du jour
- 00:05
brought to you by minor arcs like the one built
- 00:08
by know his next door neighbor and joyce and only
- 00:10
fit about a dozen animals and well they were all
- 00:12
cats You're welcome new world Oh and check out this
Full Transcript
- 00:15
diagram of a nup side down and twisted icecream cone
- 00:18
circle Why shown in the diagram above has a diameter
- 00:21
of ten centimetres If m equals forty five degrees and
- 00:24
the length of the minor arc x z is ten
- 00:27
thirds pi centimeters What is the area of the shaded
- 00:31
sector in square centimeters and hear the potential answers a
- 00:35
lot of friends So we have a nagging feeling We're
- 00:38
going to have to use our brains on this one
- 00:39
Hope we remember to bring the charger right Let's recap
- 00:41
what we know Looking at the diagram we're told that
- 00:44
the diameter of this circle is ten centimeters which makes
- 00:46
the radius this thing right here Half that or five
- 00:49
centimeters were also told that the measure of the angle
- 00:52
is forty five degrees Him right there And the minor
- 00:55
arc length of x is ten thirds pi centimeters We're
- 00:58
looking for the area of this grayish section over here
- 01:02
So what do we do next Is it time to
- 01:03
use a lifeline waken do this because circles are our
- 01:07
jam We already know that circumference equals diameter times pi
- 01:11
making the circumference of this circle ten pie since the
- 01:15
arc x z is ten thirds pi or one third
- 01:18
of the total length the angle x y z must
- 01:21
be a third of the total angle measurement as well
- 01:23
which is always three hundred sixty degrees when dealing with
- 01:25
the circle one third of three sixty is one twenty
- 01:29
What this also means is that the area of the
- 01:31
unshaded part of the circle is gonna be exactly one
- 01:34
third of the area of the total circle While we
- 01:36
need to do now is find out the area of
- 01:38
the whole circle and then take two thirds of it
- 01:40
to find the area of the shaded portion Unfortunately we've
- 01:43
had the formula for the area of a circle grafted
- 01:45
onto the inside of our islands But we know it's
- 01:48
gonna be pi times are square where are is the
- 01:51
radius The area will be pi times five squared and
- 01:55
five squared is twenty five So the area's twenty five
- 01:58
pie piece of cake Finally you have to take two
- 02:01
thirds of the total area to get shaded portion twenty
- 02:03
five five times two thirds is fifty over three times
- 02:06
pi which is answer c thank very much Xy may
- 02:09
just be a minor arc but we have a feeling
- 02:11
it's gonna make it in the big leagues one day 00:02:13.823 --> [endTime] Maybe it will get to play for the rays
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