MAth DOubts

[CHEMMASTER6000]

i can help you with vectors. do you have a specific part of vectors or is it vectors as a whole . so there eqn of a line, using 2 points, 1 directioin vector and a point. point of intersetion . foot of a line . angle between two lines. and for plane there is equn plane . finding eqn using 3 points , using another plane. then there intersection between 2 planes, angle between two planes. and plane and line which consist of angle between line and plane  and point of intersection . im sure theres abit more but i cant think of it from the top of my head. pm if you want me to go through a specific one

[Twinkle Charms]

i can help you with vectors. do you have a specific part of vectors or is it vectors as a whole . so there eqn of a line, using 2 points, 1 directioin vector and a point. point of intersetion . foot of a line . angle between two lines. and for plane there is equn plane . finding eqn using 3 points , using another plane. then there intersection between 2 planes, angle between two planes. and plane and line which consist of angle between line and plane  and point of intersection . im sure theres abit more but i cant think of it from the top of my head. pm if you want me to go through a specific one

*coughs* aheemm ill get back to you, lemme hit my books n see if sumthing gets inside.

[Alpha]

ooopps my bad, i was reading it rong ur first post...sooorrryyy and thank youu so mucchh 

No worries. And you're welcome. Lucky, today I have some time to help you.

I see you are a good fan of 'Another Cinderella story'.  

[CHEMMASTER6000]

sure

[Twinkle Charms]

Q2) Find the integral of

root of (4-x^2) ; use substitution x=2sintheta

im stuck half way :\  hellpp please =)

[Alpha]

Q2) Find the integral of

root of (4-x^2) ; use substitution x=2sintheta

im stuck half way :\  hellpp please =)

I'll use @ for theta.

x = 2 sin 2
x^2 = 4 sin^2 @

/ for root.

/ (4 - x^2) = / [4(1-sin^2@)]

Using identity sin^2@ + cos^2@ = 1,

/ [4(1-sin^2@)] = / 4 cos^2@
                        = 2 cos @

Now integrate.

Differentiation of sin@ > cos@,

Integration of cos@ > sin@.

Integrate 2 cos@ > 2 sin@.

[Twinkle Charms]

oh ohkay i got it, was skippin one step, Thank You..

[Twinkle Charms]

Q3)Integral of (50-m)^-2??

 the answer given is (50-m)^-1 buh im gettin -(50-m)^-1, where am i rong?:S

[astarmathsandphysics]

You are ignoring the - in -m

[Twinkle Charms]

You are ignoring the - in -m

ohh so we mutiply -1 in the denominator with -1 to get +1? ohkk...Thank You astar=)

[astarmathsandphysics]

is ok.

[Twinkle Charms]

Q4)Two planes have equation x+2y-2z=2 and 2x-3y+6z=3. The planes intersect in the straight line L. Find a vector equtaion for line L. 

ok so i just know to get the vector equation of a line we use this>> r=a+$p, where a is the position vector, $ is a scaler and p is direction vector, after that how to get all that i dunno....please help...=\

[CHEMMASTER6000]

so to find the direction vector you cross multiply the normals using matrices rules. and to find the point on the line you do simultaneous equation using the two plane quations but thats where it gets tricky. the trick is to sub in a value for x y or z which will give zero thus only one unknown is left. i rather not type the answer here cause its difficult to type and i dont know how to scan in the work sheet into forum ???hope it my methods helps

[Twinkle Charms]

so to find the direction vector you cross multiply the normals using matrices rules. and to find the point on the line you do simultaneous equation using the two plane quations but thats where it gets tricky. the trick is to sub in a value for x y or z which will give zero thus only one unknown is left. i rather not type the answer here cause its difficult to type and i dont know how to scan in the work sheet into forum ???hope it my methods helps

u scan ur worksheet and attach to your post cz i aint gettin what u said to do for the point on the line =\ to attach click on the additional options...

[CHEMMASTER6000]

hahaa ok i think i failed at the scanning thing but il try it here .

(a)x+2y-2z=2 and (b)2x-3y+6z=3

so point on line would be . so simultaneously solve both of them . (trick) sube 0 into one of them . i choose z

when z=0

(a)x+2y=2 (b) 2x-3y=3
 
now its easy so you can solve for x and y. sub back into eqn and walla you get the point ahh haha sound so nerdy