vThe circle below represents Earth. The radius of Earth is about 6400 km. Find the distance d, in kilometers, to the horizon that a person can see on a clear day from each of the following height h = 400 km above Earth. Round your answer to the nearest tenth of a kilometer.

What is the distance between point a and b

Secant be and cf intersect at point d inside a what is the measure of cde

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?