parallel and perpendicular lines/graphs

[dim bough]

any help on where I should start?

<@&791435371564892232>

[tribal patrol]

we need to find coordinates of point A first

you got any ideas on how to do that?

[long whale]

@tribal patrol is the answer y=2x+26

[pseudo yew]

Can you not use the coordinate of D first

Perpendicular gradient is 2x

Y - 0 = 2(x +13)
Therefore y = 2x +26

[long whale]

let’s go I got it right

what grade question is this

[pseudo yew]

I have no idea

But it's a very easy a level question I can confirm

Lemme try the other method of finding coordinate A

[neat steeple]

bc its AS

at most

[pseudo yew]

Yeah

[long whale]

A level? Damn

This was my thought process

perpendicular lines are the negative reciprocal
hence y= positive 2x
Using the coordinates of D we can say that 0 is equal to 2(-13 +c)
0=-26+c
Adding 26 on both sides we get positive 26 as c
So therefore the answer should be y=2x+26

[pseudo yew]

A level has a couple of basic gcse questions so

Yeah fair enough

U can use that method or the
Y - y1 = m (x - x1)

[tribal patrol]

you falsely assumed that the line is perpendicular

[pseudo yew]

Fairs

[long whale]

I’ve never heard of that formula before

[tribal patrol]

it's an alternative form of the equation of a line

it's called point-slope form

[long whale]

Isn’t it perpendicular?

Cuz both lines meet

So it can’t be paralel

[tribal patrol]

perpendicular means they meet at a right angle

[pseudo yew]

Ywah

[tribal patrol]

it's neither perpendicular nor parallel

the lines just intersect at some unknown angle

[long whale]

oh

[pseudo yew]

cool

[long whale]

so could my explanation be marked wrong?

[pseudo yew]

so we gotta find the coordinate of A right?

[pseudo yew]

yeah most likely

[tribal patrol]

yes

[pseudo yew]

We just need to find the distance between B and C

[tribal patrol]

yes

then use that to find A

[long whale]

Dang it I got excited

[pseudo yew]

yeah

[tribal patrol]

then now you have two points on the line, so you can find the equation fairly easily

[pseudo yew]

nah dw it happens

[long whale]

How would you do that

[pseudo yew]

oh you're so right

[tribal patrol]

tbf this is a tougher question and it probably wouldve thrown me off at gcse

[pseudo yew]

you're given the equation of the line A to C

u can use it to find the cooridnate of B and C, then work out the distance

[long whale]

I got the correct answer though right?

[pseudo yew]

Yeah I would not get this in GCSE tbh

[long whale]

It’s just the way of doing it

[pseudo yew]

Ehhhh we can't confirm that

[tribal patrol]

probably not, since your method was completely off

[pseudo yew]

because it's not confirm to be perpendicular, the gradient can't be 2x

[tribal patrol]

because the first thing you did was assume the lines are perpendicular, which we do not know

and that kinda changes everything

this sounds harsh, but you probably wouldve scored 0 marks just because of that

but it is a hard question like i said, so dont worry about it

[pseudo yew]

ye

[tribal patrol]

at point B, the line cuts through the y axis. because of this, the coordinates are just (0, y intercept) and we know from the equation of the line that the y intercept is 5

so the point is (0,5)

for point c, the line is cutting the x axis so the coordiinates would be (some x coordinate, 0)

we can see that the change in y from B to C is 5

which means the change in y from B to A is also 5

5+5=10

therefore the y coordinate of A is 10

sub that into the equation to find the x coordinate

now you have points A and D - you have two points which means you can form the equation of the line going between them

[dim bough]

sorry I had to go

[tribal patrol]

that's fine

but do you understand my explanation?

[undone geode]

here is my working

[cinder dagger]

yh suprising to see it in a yr10 assignment

unless u just doing past paper questions

[undone geode]

i'm not the OP

[long whale]

Nah I just saw it in the thread

[cinder dagger]

yh OP is also yr10

[long whale]

I thought I could do it but I couldn’t

[cinder dagger]

fair enough

[undone geode]

no it's a yr 11

look at their role

[cinder dagger]

maybe it hasnt updated for me

[undone geode]

this dude sent it tho not him

[cinder dagger]

ohh mb i got confused

ur right

[pseudo yew]

Is this actually a gcse question

Cus icl I've only done these questions in a level

[undone geode]

it's a noice question

[tribal patrol]

very well could be

doesn't require any a level content

[undone geode]

there's not too much difficult about it

[pseudo yew]

Fair enough tbh

[undone geode]

but at first sight u might think it's perpendicular lines

[tribal patrol]

yeah

that's the main problem with it

[pseudo yew]

That's probably why then

Hoping I didn't make this mistake in my A level exam 💔

[long whale]

@dim bough where did u find the question

[iron ginkgo]

that's what I suggested but deleted it since it never explicitly stated that they were perpendicular so I took it back

[pseudo yew]

Yeah smart 😭

I shouldn't be making these mistakes, but I'm done with a levels so there's no real consequences x

[iron ginkgo]

I'm just so used to seeing them being perpendicular 😭 😭

[iron ginkgo]

valid

[pseudo yew]

Same 😭😭

[dim bough]

I'm y10 just changed it early lol

[dim bough]

teacher assigned it

[dim bough]

no sorry

[undone geode]

refer to this

[dim bough]

will do

why did you equate it to 0?

[undone geode]

sub into y=mx+c

point C is when y = 0

so sub 0 as y

into the equation of line ABC

find x and that gives u the x coordinate for the point

[dim bough]

ohh I see

does the starting say 10 or 0?

[undone geode]

10

and using the fact that AB = BC u can conclude the bit in red

[dim bough]

oh

it was quite simple

thanks all

what's the command to close this post?

[undone geode]

eh u can just leave it open it's fine

not sure how to close it myself

[dim bough]

oh alright

[neat steeple]

right click on ur thread under #1020087693197189150 and there should be an option to close

[dim bough]

yeah