circle theorems

[celest whale]

Ok

What circle theorems do you know involving a diameter

[open wasp]

none tbh

we just copied them out and then my teacher didn’t teach us them

[celest whale]

Something about semicircles

[open wasp]

i watched the vid and i followed the steps and it was wrong i don’t understand

like the answer i got from following the vid

[celest whale]

Ok

So angle in a semicircle is a right angle

[open wasp]

BCA = 5 BAC

[celest whale]

That’s abc

[open wasp]

okay

so then

[celest whale]

So we know the other 2 angles add to 90

[open wasp]

180 = BCA + 5BAC ??

[open wasp]

do i divide 90 by 6?

[celest whale]

It would be 90 = bca + bac

And we know bca is 5bac

[open wasp]

why not times 5

ok

[celest whale]

So we have 90 = 6bac

So yes we divide by 6 to get angle bac

[open wasp]

thanks

can u help on another

[celest whale]

That’s the same one

[open wasp]

it’s not

i put in my answer and it was wrong

nvm did it

[celest whale]

Same as last time

We know adc and abc are right angles

Ooh

Nvm

It’s a cyclic quadrilateral

Do you know that circle theorem

[open wasp]

no

[celest whale]

Opposite angles in a cyclic quadrilateral add to 180

So dcb is 82

[open wasp]

idk what a cyclic quadrilateral is i’m gonna be real

[celest whale]

Just a quadrilateral in a circle where all 4 point touch the circumference of the circle

[open wasp]

CBA = 90
CBA = 90
DCA = 47
BCA = 35
so does
DCA + BCA = 82

so DCB is 82

wait

and then

180- (35+90) = 55?

and

180-(47+90) = 43

so is DAB 43+55

[celest whale]

That’s one way

Or just do opposite angles add to 180 so 180-(35+47)

[open wasp]

oh