Name a point non-coplanar to plane K

Asource of laser light sends rays ab and ac toward two opposite walls of a hall. the light rays strike the walls at points b and c, as shown below: what is the distance between the walls?

The length of time it takes to find a parking space at 9 a.m. follows a normal distribution with a mean of 5 minutes and a standard deviation of 2 minutes. find the probability that it takes at least 8 minutes to find a parking space. (round your answer to four decimal places.)

Lines a and b are perpendicular. if the slope of line a is 3, what is the slope of line b?