coordinate geo Help pls :( (1 Viewer)

[AnandDNA]

Um there is this diagram in my textbook so ill try to describe the graph

There is a line that goes through the x axis and the y intercept is 4 and the angle of inclination is 45 degrees. There is a second line that passes through the same y intercept and x but comes from up left to down there is an angle on the right of the line that says 120 degrees. Um the two lines are perpendicular and one has a negative x intercept and the other has a positive x intercept.

the question asks to find the equation in general form for both lines.

sorry for my crappy description if u need more clarification on the decription pls post and ill reply

Yeh i just wanted to know where to start from. I know that i shud do Tan45 which equals 1 so that teh grad for one line. but i dont know what to do from there.

 

[AnandDNA]

nvm this i worked it out. Just had to put it in y=mx+b den put in general form :jaw: .

 

[sicmacao]

The two lines are not perpendicular. They intersect at 75 degrees. Probably the diagram is not drawn to scale. the second line shoud inclined an angle of 135 degree.

The equation of the first line is y = x + 4 since 45 degree -> m=1
The general form will be x-y+4=0 using y=mx+b, m=1, b=4

Assuming the lines are perpendicular m1 * m2 = -1
So the line grad = -1 y intercept = 4
so equation of the second line is y= -x +4 using y=mx+b, m=-1, b=4
The general form will be x+y-4=0

 

[AnandDNA]

yeh is saw the mistake tu lol. i just assumed they werent perpendicular and did tan120=-sqrt(3) and den solve using point intercept form..

Um i have another question lol.
I did most of the question just my answer for one of dem is different to textbook answer. There are 3 points A(4,3) B(0,-3) C(4,0)
find the area of OABC Im guessing O is orgin lol. Oh and OABC is a parallelogram

I found BC distance as 5 units^2 and AC distance as 3units^2 and the formula for area of parallelogram is bxh so my anwer is 15 but book says 12 so just wanna know where i made the mistake.

I

 

[AnandDNA]

disregard this i found my mistake the base is actually the difference in x coordinates and the height is difference in x corrdinates