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| bio | website | |
|---|---|---|
| location | ||
| age | ||
| visits | member for | 2 years, 5 months |
| seen | 19 hours ago | |
| stats | profile views | 140 |
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Dec 20 |
answered | How do you solve the area of a trapezoid using diagonals |
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Dec 16 |
revised |
Green's Theorem - Trouble understanding problem Added LaTeX for equation. |
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Dec 16 |
suggested | suggested edit on Green's Theorem - Trouble understanding problem |
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Dec 14 |
awarded | Yearling |
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Nov 26 |
comment |
surface unit sphere What do you mean by $Z^2$? From the context it appears that you intend $Z\cdot Z$, but that would always yield a value of 1. |
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Oct 31 |
comment |
Determine the numerical method What is the context? |
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Oct 4 |
comment |
How do I solve Ax = 0? X is in the span of eigenvectors which are associated with 0 eigenvalues. |
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Oct 2 |
comment |
3D points rotation to quaternions Note that what you are describing is not a pure rotation. The vector p2-p1 gets longer through the rotation. |
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Sep 24 |
comment |
Gram-Schmidt Orthogonalization for subspace of $L^2$ It is required so that $\Vert e_2 \Vert = 1$ |
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Sep 23 |
comment |
How do you explain the appearance of a sine in the integral for calculating the surface area of a sphere? The question is not so much where does the 2 come from, rather it is why is the area of the tube equal to $2\pi\cdot\pi$ and the area of the sphere equal to $2\pi\cdot 2$. In both cases the area of a thin strip extending from N to S is $\pi d\theta$ and $2d\theta$ respectively. |
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Sep 23 |
comment |
Knowing coordinates of a point having two coordinates and the distance. Please clarify your question: What do you mean by geographic coordinates? Lat, long, Alt? If so, linear interpolation would be sufficiently accurate for distances of 15cm. |
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Sep 23 |
comment |
How do you explain the appearance of a sine in the integral for calculating the surface area of a sphere? Because the strip represented by the half great circle is not constant in width. It is wider at the equator than at either pole. Your approach would be correct for a cylindrical tube of height $\pi$ and radius 1. |
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Sep 20 |
comment |
Does a vector set span another vector set F is rank 3, therefore it spans $\mathbb R^3$, so any vector $\mathbf v$ in $\mathbb R^3$ will be in the span of F. E on the other hand is rank 2 (column 2 & 3 are linearly dependent) therefore, not all vectors in $\mathbb R^3$ are spanned by E. Part (b) shows that the columns of F are not spanned by E. |
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Sep 16 |
answered | Help me name or find the existing name for this geometric concept! |
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Sep 14 |
awarded | Necromancer |
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Sep 12 |
comment |
Projectile Motion of a cannonball 1. you only need vertical velocity. What is time when velocity is zero? What is height at that time. 2. What is time when displacement returns to original position? use that time with horizontal velocity to get distance. 3. Determine vertical speed given time. Then combine with horizontal speed. 4. Use time from (3) and use displacement formula. |
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Sep 8 |
comment |
Coplanar points Also notice that I corrected a typo in my edit. I had developed a lengthy post more fully explaining the geometry but Chrome crashed and I lost the whole thing :(. |
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Sep 8 |
comment |
Coplanar points @JohnSmith, 1. Since the mean has been removed the plane passes through the origin. Then the equation of the plane is given by a*x + b*y + c*z = 0. Let U = [a b c]' and v = [x y z]'. Then the equation of the plane becomes v'*U = 0. Note that v is any point in the plane and U is perpendicular to the plane (by definition). 2. in the above decomposition D represents the eigenvalues of the matrix A. IF the points are not perfectly co-planar, then generally v_i'*U != 0 for all v_i. In other words there are small porions of v_i that project onto U. |
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Sep 8 |
revised |
Coplanar points added 1 characters in body |
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Sep 8 |
comment |
Coplanar points See above edit. |
