The main difference between arctan and arcsin lies in the range of values they can output. Arctan, or the inverse tangent function, takes in a ratio of the opposite and adjacent sides of a right triangle and outputs an angle in the range of -π/2 to π/2. On the other hand, arcsin, or the inverse sine function, takes in a ratio of the opposite and hypotenuse sides of a right triangle and outputs an angle in the range of -π/2 to π/2. In other words, arctan outputs angles in the range of -90 degrees to 90 degrees, while arcsin outputs angles in the same range. **

The arctan function and the calculator both work, but they may produce different results in certain cases. The arctan function is a mathematical function that returns the angle whose tangent is a given number, while the calculator uses a numerical approximation to calculate the arctan. In some cases, the calculator's approximation may not be as accurate as the mathematical function, leading to slightly different results. However, in general, both the arctan function and the calculator are reliable tools for calculating inverse tangent values. **

To calculate the arctan in polar coordinates, you can use the formula: θ = arctan(y/x), where (x, y) are the coordinates of a point in the plane. This formula gives the angle θ between the positive x-axis and the line connecting the origin to the point (x, y). The arctan function returns the angle in radians, which can be converted to degrees if needed. This angle can then be used to represent the point in polar coordinates as (r, θ), where r is the distance from the origin to the point. **

To prove the continuity of arctan(x), we can show that the function arctan(x) is defined for all real numbers x and that it is continuous at every point in its domain. One way to do this is by showing that the limit of arctan(x) as x approaches a is equal to arctan(a) for all real numbers a. This can be done using the properties of the arctan function and the definition of continuity. Additionally, we can also show that the arctan function is differentiable for all x in its domain, which implies that it is also continuous. **

The delivery times of DHL Express courier vary depending on the service chosen. DHL Express offers different delivery options such as next-day delivery, two-day delivery, and standard delivery. The delivery times also depend on the origin and destination of the shipment. Customers can track their shipments in real-time to get updates on the estimated delivery times. **

The delivery service did not deliver due to unforeseen circumstances such as extreme weather conditions, road closures, or vehicle breakdowns. These factors may have hindered the delivery service's ability to fulfill their obligations within the expected timeframe. Additionally, there could have been a high volume of orders leading to delays in delivery. **

The delivery times of DHL Express courier service vary depending on the destination and the service chosen. Generally, DHL Express offers delivery within 1-3 business days for international shipments and next business day delivery for domestic shipments. Customers can also opt for specific time-definite delivery options for added convenience. It is recommended to check the estimated delivery times based on the specific destination and service selected when using DHL Express courier. **

Yes, some delivery services do deliver on holidays, while others may have limited or no delivery service on holidays. It ultimately depends on the specific delivery service and their holiday schedule. It's best to check with the specific delivery service to see if they offer delivery on holidays and what their holiday schedule is. **