Coordinate geometry (2 Viewers)

[Fortian09]

Lol need help again


Find the angle of inclination of the line joining the given points

(-3,4) and (2,9)

Given A = (k,3) and B = (-2,k+7). If AB=10 find the value(s) of k.


L is a line passing through (4,3) with slope -3/4
a) find the equation of L
b) Find the area bounded by the line (L) and the positive axes

Thasts all i got for now
thanks folks

 

[lsam]

Lol need help again


Find the angle of inclination of the line joining the given points

(-3,4) and (2,9)

Given A = (k,3) and B = (-2,k+7). If AB=10 find the value(s) of k.


L is a line passing through (4,3) with slope -3/4
a) find the equation of L
b) Find the area bounded by the line (L) and the positive axes

Thasts all i got for now
thanks folks

first: m = 9-4/2+3 =5/5 =1
tan @ = 1
@ = 45 degrees or pi/4 radians

second: SQR(k+7-3)^2 + (-2-k)^2 = SQR k^2 + 8k + 16 + k^2 + 4k + 4
= SQR 2k^2 + 12k + 20
So 2k^2 + 12k + 20 = 100
2k^2 + 12k - 80 = 0
k^2 + 6k - 40
(k+10)(k-4)

I quickly did 1-2 but I think I will get banned soon so don't expect me to finish Q3.

third: y - 3 = -3/4(x-4)
4y - 12 = -3x + 12
3x + 4y - 24 = 0

b) y = 0 when x = 8 and x = 0 when y = 6

A = b . h /2
= 6 . 8 /2 = 24

I am not even sure my answers would be correct as I did it really hurriedly under the fear that I might be banned before I answer all these. cya

 

[Fortian09]

that was heaps fast...
but can someone explain y i have to use tan in qn 1?

 

[conics2008]

you use tan @ because the graident can also be obtained by tan @

 

[Fortian09]

i have another qn

The line joining a point P on the y-axis and the point Q = (-2SQR3, 2) has inclination of 120^o. find the coordiates of P.


Given A=(7,6), B= (8,-2). C is a point on the x-axis and ACperpen.BC. Find the coordinates of C.

And what is the altitude of a triangle or something?

 

[lolokay]

tan120 = -rt3
P = (0,a)
and (2-a)/-2rt3 = tan120 = -rt3
2 - a = 6
a = -4
P = (0, -4)

the circle containing (7,6) and (8,-2) as a diameter (any point C, other than A or B, on the circle has condition that ACperpBC since the triangle formed at the diamater is a right triangle)
has the equation (x-7.5)² + (y-2)² = 65
when y=0
(x-7.5)² = 61
x = +- rt61 + 7.5
so C=(+-rt61 + 7.5, 0)

altitude of a triangle is the line from a vertex perpendicular to the opposite side

not sure if answers are right

 

[doink]

I think you should drop 3u

 

[Fortian09]

I think you should drop 3u

is that directed at me or lolokay?

 

[omniscience]

is that directed at me or lolokay?

Most likely towards you.

 

[Aerath]

is that directed at me or lolokay?

Not that you're obliged to listen to him or anything.

 

[tacogym27101990]

Which is better/easier.. chemistry or physics?

pretty random question
but for me chemistry is easier and more interesting
because i have a hopeless physics teacher
who cant explain the simplest of things
and that took my interest away from it
seems like a cool subject when i read thetextbook though

 

[tacogym27101990]

umm well id probably go with chemistry
physics would be good if you had a good teacher though
so find out what the physics teachers like and then choose
i did all three in yr 11
biologys a huge bludge
i was topping the year with no study in it ( wish id kept it =[)
but i can be pretty boring

 

[vds700]

Which is better/easier.. chemistry or physics?

id say chem is harder (more content) than physics (more concepts).

Physics is probably more interesting imo.

Really depends on what u want to study at uni (assuming u are going to), also what u find interesting, like u do a bit of chem and physics in junior science etc.

 

[Aerath]

For me - Phys is easier.

 

[kaz1]

For me Chemistry is easier.

 

[Fortian09]

AHHH stupid easy coord geometry and I'm FRIKIN STUCK!!
someone help me!

to the pro math people this will be a breeze...

Find the equations of the straight lines which pass through the intersection of the lines 2x-y+2=0 and 3x-4y-2=0, and satisfy the following conditions:

1. Perpendicular to the x-axis

2. Perpendicular to the y-axis


Find the equation of the line which passes through the intersection of the lines 2x+y-4=0 and 2x-3y=0, and is perpendicular to the y-axis.

A line passes through the intersection of the lines x+2y-3=0 and 2x+y+3=0. It is also perpendicular to the line joining the intersection and the origin. Find its equation.

A line passes through the intersection of the lines 3x+2y-15=0 and 3x-y=0. If the area of the triangle enclosed by the line and the axes is 25/4, find the equation of the line.

A line passing through the intersection of the lines
L₁: 2x-3y+5=0 and L₂:x-4y+5=0 is drawn such that it makes 45deg with the line L₃: 2x-3=0. Find the equation of the line drawn

 

[tommykins]

AHHH stupid easy coord geometry and I'm FRIKIN STUCK!!
someone help me!

to the pro math people this will be a breeze...

Find the equations of the straight lines which pass through the intersection of the lines 2x-y+2=0 and 3x-4y-2=0, and satisfy the following conditions:

1. Perpendicular to the x-axis

2. Perpendicular to the y-axis

2x-y+2 = 0 (1)
3x-4y-2 = 0 (2)

(1) y = 2x + 2

(1) -> (2)

3x-4(2x+2) -2 = 0
3x - 8x - 8 - 2 = 0
-5x - 10 = 0
x = -2

3(-2) - 4y - 2 = 0
-6 - 2 -4y = 0
-8-4y = 0
y = -2

1. Perpindicular to the x axis is y = -2
2. Perpindicular to the y axis is x = -2

Find the equation of the line which passes through the intersection of the lines 2x+y-4=0 and 2x-3y=0, and is perpendicular to the y-axis.

2x+y-4 = 0 (1)
2x-3y = 0 (2)

(1)-(2)
4y - 4 =0
y = 1

2x-3 = 0
x = 3/2

Perpindicular to y axis is x, so x = 3/2 is the line.


The rest of the questions are like this.

 

[Fortian09]

Is there a way to do these questions using the 'k'' method?

 

[lyounamu]

Is there a way to do these questions using the 'k'' method?

You wouldn't use that here because you are trying to find an equation that is directly related to the points of the intersections.

 

[Fortian09]

hmm wat cases can i use the 'k'; method other than passing through points and parallel and intercepts?


Btw tommy I'm sorry if i confused you but the perpendicular to y and perpendicular to xquestions are seperate and i dont htink they relate to each other