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Geometry and Measurement Videos 88 videos

SAT Math 1.1 Geometry and Measurement
719 Views

SAT Math 1.1 Geometry and Measurement. What is the circumference of the circle?

SAT Math 1.2 Geometry and Measurement
246 Views

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
267 Views

SAT Math 2.3 Geometry and Measurement. Find the length of AB.

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SAT Math 9.1 Geometry and Measurement 261 Views


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Description:

SAT Math 9.1 Geometry and Measurement

Language:
English Language

Transcript

00:02

Here’s your shmoop du jour, brought to you by parallelograms.

00:06

The Leaning Tower of Pisa of rectangles.

00:11

Given that ABCD is a parallelogram, find the value of y.

00:17

Here are the potential answers...

00:19

Well, we’re really only given one piece of information, other than in the diagram…

00:24

…which is that we’re looking at a parallelogram.

00:27

We know a few things about parallelograms…and one of those things is going to help us a ton here.

00:32

Opposite sides of a parallelogram are always equal in length.

00:39

That tells us that 6x – 6 = 4x + 5…

00:43

…and 8y + 3 = x – 5.

00:47

We’ll start with the first one so we can nail down the value of x.

00:50

Watch your fingers.

00:51

If we subtract 4x from both sides…

00:54

…and add 6 to both sides…

00:55

…we get 2x = 11.

00:58

Dividing both sides now by 2, we see that x = 11/2.

01:04

Now we can take that value and throw it into our other equation…

01:07

…which becomes 8y + 3 = 11/2 – 5.

01:11

5 can be rewritten as 10/2…and 11/2 minus 10/2 is just… 1/2.

01:19

We can subtract 3 from both sides to get 8y = -2 1/2.

01:23

When dividing both sides by 8, we may want to rewrite that part on the right as -5/2,

01:29

to make things easier.

01:31

-5/2 divided by 8 is the same as multiplying it by 1/8…

01:36

…which comes out to -5/16.

01:38

Answer C.

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