膽大如斗是民間諺語，其意思是指膽量極大。
這個諺語的形成有一個故事：據說這個人平時並不敢穿太顯眼的衣服，一天他看到人們都把貴重的東西往斗里裝，他覺得貴重的斗很吸引人，於是就將斗裝滿黃沙扛在肩上，大搖大擺的走在鎮上，人們看見他這副模樣，無不佩服他的膽大，從此，"膽大如斗"這句俗語就傳了下來。
這句諺語多用來形容某人的膽子非常大。What is the formula for calculating the area of a circle?
The formula for calculating the area of a circle is πr^2, where r is the radius of the circle and π is the mathematical constant known as pi. The formula is used to calculate the area of a circle based on its radius, which is a measure of the distance from the center to the edge of the circle.
To use the formula, simply plug in the radius of your circle into the equation to find its area. Note that the formula assumes that the radius is positive, and if it is negative, you can simply multiply the result by -1 to get the correct area. Additionally, if you are working with very large or very small values, you may need to use scientific notation or take other precautions to avoid numerical errors.