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Geometry and Measurement Videos 87 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 1.3 Geometry and Measurement. Find the length of CE.
Calculating the Bisector Length of a Square 2 Views
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Description:
The figure above is a square with a side length of . What is the length of ?
Transcript
- 00:02
Okay Satay shmoop er's Another picture for you We got
- 00:05
a b c d here and one side's five times
- 00:08
grow to this looks like a square but we don't
- 00:10
see any of those right angle thing You so we
- 00:12
can assume it yet let's See what they say the
Full Transcript
- 00:15
figure above the square Ok so what now We can
- 00:17
assume it with a side of length Five times where
- 00:20
to what's the length of a d All right Well
- 00:26
see the problem is special here You sure all problems
- 00:29
are unique Yes Your all problems are unique snowflakes whose
- 00:33
parents love them very much But cutting this square in
- 00:36
half makes two special right triangles So this problem is
- 00:39
well you know extra special So we just put in
- 00:41
the forty five degree lines there in a little box
- 00:44
thing He's there you had partial credit You'd lose Get
- 00:47
two points for all that Well the ninety degree corners
- 00:49
are perfectly divided in half by that by sector So
- 00:52
that splits the angle into two forty five degree angles
- 00:54
When the angles of a right triangle are forty five
- 00:56
forty five and ninety the triangle is called Yes a
- 00:59
special triangle So there we go We've got x and
- 01:02
then x and x times grow too well The two
- 01:05
legs are equal courtesy of the two equal angles and
- 01:08
the high pot news is a screw to two times
- 01:10
greater than legs Well one of the sides already has
- 01:13
a square to to there But if we multiply that
- 01:15
by the square root of to to get a d
- 01:17
well what happens This happens It looks like this five
- 01:20
times grow two times Two is five times two or
- 01:23
just ten So eighty is ten that's it And yes
- 01:27
we could've used the pythagorean theorem in the beginning and
- 01:29
just squared all sides and gotten you know square root
- 01:32
of this five times for two squared plus five from
- 01:34
room c squared You'll get fifty plus fifty a c
- 01:37
squared or one hundred and it's road one hundred ten
- 01:40
Yeah The diagram of the square can't equal the length
- 01:42
of the side so that sea would have been impossible
- 01:46
in the length of five times were over too well
- 01:48
that comes from cutting one of the sides in half
- 01:50
If you remember the this ratio this acts money maximum
- 01:54
Ratio for a forty five Forty five Ninety triangle but
- 01:56
to divide length by expert to instead of multiply well
- 01:59
then we'd get a diagonal of five as in be
- 02:02
so that ain't it either So just go with the 00:02:05.21 --> [endTime] war shmoop
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