Parallel Rays of Sun

Is Sun Rays Parallel?

Parallel sunlight The radiant energy of the sun spreads in every direction. However, since the sun and the earth are far apart, we assume that they are usually almost parallel. Ancient Greece’s Eratosthenes measured Earth’s size quite accurately, assuming that … more

Parallax of Eyes

Parallax of Eyes

Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you measure the distance? Humans … more

Ellipse

Ellipse

Ellipse An ellipse is a closed curve connecting the points that the sum of the two distances to the focal points is a constant. The ellipse’s longest diameter is the major axis, and the shortest diameter is the minor axis. … more

Differentiation

Differentiation

Differentiation The differentiation is to find the amount of change at a point on a graph f(x). This is like the process of finding the slope of the tangent line when you can draw a tangent at a point on … more