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Geometry and Measurement Videos 87 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 1.3 Geometry and Measurement
231 Views

SAT Math 1.3 Geometry and Measurement. Find the length of CE.

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SAT Math: Calculating a Circle's Radius When Given Its Center and a Point on Its Circumference 1 Views


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Description:

What is the radius of a circle with a center at (-4, 5) and a point on the circumference at (2, 13)?


Transcript

00:00

Yeah Whoa Okay A satay mash bumpers moron circles What's

00:06

the radius of a circle in the center and negative

00:07

for five and a point on this Or conference at

00:10

two Thirteen So there are two ways to tackle this

00:15

problem but usually we play two hand touch Teo keep

00:18

from hurting it because math problems don't wear protective headgear

00:22

Well here's a standard form circle where H K's a

00:24

center Yeah you know this one Well plug in the

00:26

centre point for H and K being careful about the

00:29

signs Yeah I saw the sign song about that So

00:32

we've got X plus four squared Plus Wyman five squared

00:36

equals R squared were only given a random point on

00:39

this circle And we can put that point to good

00:41

use So just plug it in for X and y

00:43

It's how easy this is We love circles so we

00:45

get two plus four squared plus theta two minus five

00:47

squared equals R squared Well six squared plus eight square

00:50

It is you thirty six plus sixty fourths Hundreds are

00:54

scared So are squared of one hundred which is in

00:56

the radius of the circle Just ten Yeah well that

00:59

was one way to solve the problem Another way would

01:01

be with a distance formula the distance from the centre

01:04

to any part of the circle's edge Is the radius

01:06

rights basically the definition Well we could have used the

01:09

distance formula to measure the distance from the center to

01:11

a random spot on the edge by plugging in the

01:13

values of the two points that were given like this

01:16

So the distance is ah this thing And then we

01:19

just plug in the negative four minus two squared plus

01:22

five minus thirteen square there And that gets us formula

01:26

Looks a whole lot like what we just did only

01:28

coming at it from a side view mirror Well either

01:30

way works but whichever you choose tackle it gently so 00:01:33.23 --> [endTime] it's Mom doesn't get too worried and that's it

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