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Mathematics 8 Online
imyoursgirlsgirl:

ss below

imyoursgirlsgirl:

imyoursgirlsgirl:

@AZ

imyoursgirlsgirl:

?

AZ:

okay, so this one is going to be a little bit more work but just bear with me Do you remember the formula from the previous problems? angle = 1/2 * (big arc - small arc)

imyoursgirlsgirl:

yes

AZ:

so what is the big arc in the image and what is the small arc? use the letters on the circle

imyoursgirlsgirl:

the big arc is wz and the small one is xy

imyoursgirlsgirl:

@AZ

imyoursgirlsgirl:

@florisalreadytaken

AZ:

Good! And the angle is P so far we have P = 1/2 (WZ - XY) Do you agree?

AZ:

Now WZY = 200 WZY is basically WZ + ZY and that equals 200 Now if that equals 200, what does the rest of the circle equal? The entire circle adds up to 360 so what is 360 - 200 = ?

imyoursgirlsgirl:

im sorry i didnt respond something happened to my brother

imyoursgirlsgirl:

@AZ its my last question

AZ:

okay, I hope your brother is fine read my last comments and respond to it

imyoursgirlsgirl:

its 160

imyoursgirlsgirl:

and yeah he will be ok

imyoursgirlsgirl:

its ok thanks for looking at it

BlaccPanda:

no problem :D

AZ:

so the rest of the circle is 160 that means WXY is 160 do you agree?

imyoursgirlsgirl:

yes

AZ:

and WXY is WX + XY right?

imyoursgirlsgirl:

yes?

AZ:

so now let's put everything together you said the big arc was WZ and the small arc was XY and so the formula for the angle was P = 1/2 (WZ - XY) and now we know WZY is equal to WZ + ZY = 200 and WXY is equal to WX + XY = 160 Do you follow still?

imyoursgirlsgirl:

kinda but yes

AZ:

okay, do you see in the image how there's that red dash on the both lines?

AZ:

that just means that those two line segments have the same length which means that the arcs opposite that are the same so basically WX = ZY

imyoursgirlsgirl:

ok

AZ:

okay so you know how we have P = 1/2 (WZ - XY) we want to substitute those two other equations into this one so we can solve for P

AZ:

WZ + ZY = 200 can you solve for WZ

imyoursgirlsgirl:

yes

imyoursgirlsgirl:

it would be half right

AZ:

no, it would just be WZ = 200 - ZY

AZ:

can you do it similarly for WX + XY = 160 solve for XY just subtract WX on both sides

imyoursgirlsgirl:

ya lost me

imyoursgirlsgirl:

again :(

AZ:

so basically, think of it like apples and oranges WX is an apple XY is an orange WX + XY = 160 apple + orange = 160 now what is an orange? orange = 160 - apple does that make sense?

imyoursgirlsgirl:

so i have to divide 160?

AZ:

no

AZ:

you only divide if you were multiplying before to move it to the other side now we need to substitute it in

imyoursgirlsgirl:

ok

AZ:

P = 1/2 (WZ - XY) WZ = 200 - ZY XY = 160 - WX and remember how we said ZY = WX so instead having both, we can just one for consistency WZ = 200 - ZY XY = 160 - ZY

AZ:

let me add colors \( P = \dfrac{1}{2} (\color{red}{WZ} - \color{lime}{XY})\) \(\color{red}{WZ} = 200 - ZY\) \(\color{lime}{XY} = 160 - ZY\)

imyoursgirlsgirl:

ok what about them now

AZ:

you plug it in \( P = \dfrac{1}{2} (\color{red}{200 - ZY} - (\color{lime}{160 - ZY}))\)

imyoursgirlsgirl:

ok so 200-160 then divide by 2

AZ:

exactly

imyoursgirlsgirl:

ohh ok ill do that

imyoursgirlsgirl:

i got 920.5?

imyoursgirlsgirl:

oops i pressed plus sorry

imyoursgirlsgirl:

its 20

AZ:

There you go

AZ:

This question was so long and extra

imyoursgirlsgirl:

yeah it was

imyoursgirlsgirl:

but thx

AZ:

you're welcome

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