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Mar
5
revised Find $z$ of a point in a plane in 3D space
added 868 characters in body
Mar
5
comment Find $z$ of a point in a plane in 3D space
I know, I saw your age in your profile. :) Have you seen systems of linear equations before? I would have added some more wikipedia links, they may not be helpful beyond the the introduction before the table of contents (e.g. Coplanarity. Some things that come up when googling "vectors introduction" look more helpful.
Mar
5
revised Find $z$ of a point in a plane in 3D space
added 292 characters in body
Mar
5
answered Find $z$ of a point in a plane in 3D space
Mar
5
comment Find $z$ of a point in a plane in 3D space
Imagine $a=b=c=0$ and $d=1$. Then your four points form a (non-regular) tetrahedron and there may be many or no points inside it with given x and y. Also, even if $A,B,C,D$ form a quadrilateral in space (that is, they all lie on the same plane), I do not think they will form a square unless $a=b=c=d$.
Mar
5
revised Find $z$ of a point in a plane in 3D space
geometry tag added
Mar
5
suggested suggested edit on Find $z$ of a point in a plane in 3D space
Mar
5
comment Find $z$ of a point in a plane in 3D space
(1) Is your problem only the z coordinate or also whether the point is side the shape? (2) Can you be sure the four given points are in the same plane? (3) Are you familiar with vectors?
Feb
21
answered How do I complete this identity?
Feb
18
awarded  Organizer
Feb
18
revised Car chase trajectory and time
changed tags
Feb
18
suggested suggested edit on Car chase trajectory and time
Feb
18
comment Car chase trajectory and time
The 2D case works like 2 1D cases, except that you do not know Car1's speed in x-direction or Car1's speed in y-direction, only a combination of both, which gives you a system of 2 equations to transform and insert into a third one, ultimately solving a quadratic equation, no matter whether you derive them from a vector-based approach, coordinates, or else. Again, what did you try?
Feb
18
comment Car chase trajectory and time
Did you try to use vectors? Also, "angle of 60" relative to what? The line connecting Car1 and Car2? The x-axis?
Feb
18
awarded  Yearling
Feb
18
comment Geometric construction of 2 soap bubbles meeting
Do I understand this correctly that you take "meet at angles of 120°" as given? Or do you want to derive this fact after the construction of the dividing wall as asked in the question?
Feb
18
answered Geometric construction of 2 soap bubbles meeting
Jan
29
awarded  Commentator
Jan
24
revised Coefficient of $x^4$ in multinomial expansion
alternative approach with binomial theorem
Jan
24
comment Coefficient of $x^4$ in multinomial expansion
Why do you have to use the binomial theorem here? Using distributive law (and some combinatorics, incl. some binomial coefficients) would require less calculation.