The circumference of a circle refers to the total length of the curve when it is laid out flat.
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A ring, also called an annulus in geometry, refers to the part left when a smaller concentric circle is cut out of a larger circle, basically like a hollow circle.
A circle is a type of geometric shape, defined as the figure formed when a line segment rotates all the way around one of its fixed endpoints in a plane.
Cosmology is a branch of astronomy that studies the overall structure, evolution, and origin of the universe. Its core content includes the standard model made up of dark energy and dark matter, and it reveals the large-scale features of the universe through observations and theory. This field combines physics, philosophy, and other areas, is based on general relativity, and relies on observational techniques like cosmic microwave background radiation and supernova redshift to test theoretical models.
Cosine is a type of trigonometric function in math. Simply put, in a right triangle, it's the ratio of the length of a sharp angle's adjacent side to the length of the hypotenuse.
The remainder is the number left over when integer division doesn't divide evenly, and it has to be smaller than the divisor and can't be negative.
Significant figures are all the digits from the first non-zero digit on the left to the last digit, used to reflect the measurement accuracy.
A rational number is a number that can be written as the ratio of two integers (in fraction form). In math, integers and fractions are both generally called rational numbers.