# Tagged Questions

2answers
223 views

### Finding the position of a moving point [closed]

A point is moving on a given curve. For example, curve equation is: $$x^2 + y^2 - 10y = 0,$$ which is a circle with $5$ meter radius. If point is on $(0,0)$ at $t = 0$ and is moving on the curve ...
1answer
49 views

### Geometric meaning of a matrix decomposed into its symmetric and skew-symmetric parts

What's the geometric meaning of a matrix decomposed into its symmetric and skew-symmetric parts? For example, a skew-symmetric matrix on its own can be interpreted as an infinitesimal rotation. As ...
1answer
135 views

### Littlewood's orbital joke

In A Mathematician's Miscellany, Littlewood offers this item: To determine the orbit of a planet or comet 3 observations, each of two (angular) co-ordinates and the time t, suffice. It is ...
2answers
95 views

### Sketching phase portraits [closed]

I am trying to answer this question: I would like to know how I go about drawing a phase portrait. All of the examples in my notes are simply the solution with no explanation, and this method of ...
1answer
64 views

### Is the shadow of the earth coming up almost matching in size with the moon a coincidence?

The fool that I am, today was the first time I wondered how come the shadow of the earth is almost same in size as the moon. I mean, as I was looking at the crescent moon in the evening, it came upon ...
2answers
135 views