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Learn how the number Pi allows us to relate the radius, diameter, and circumference of a circle.

我们为什么称之为「弧度」（radians）呢？ 这名称看上去很接近单词「半径」（radius）。 一种解释是，当我们用此处的弧长 除以半径时， 相当于是在求几倍的半径 才等于问题中的弧长。 比如，在这 …

We call the radius of the circle associated with each point the radius of curvature at that point. It's a good way to measure how much a curve actually, you know, curves at each point.

Saiba como o número Pi nos permite relacionar o raio, o diâmetro e a circunferência de um círculo.

Practice finding the radius and diameter of a circle using both vocabulary and visuals.

Could you replace the coordinate system with two perpendicular imaginary number lines and take the negative square root of the radius to also get a circle? If this is the case, then can you somehow plot …

So we could say that our radius of convergence is equal to 1. Another way to think about it, our interval of convergence-- we're going from negative 1 to 1, not including those two boundaries, so our …

So if you were to take the Earth's radius and add it to the moon's radius, the sum of those two radii, the ratio of that sum to Earth's radii is the square root of phi.

How would you solve this problem if you were given the radius of the circle instead of the circumference?