Question

Brenda observes that the keyboard and the screen of an open laptop lie on two different planes. In how many lines do the planes containing the keyboard and the screen intersect?

Answer 1

Two planes can:
1) never intersect when parallel,
2) intersect across infinite lines when coplanar, and
3) intersect on one line otherwise.
You gave an example of number 3.
Two planes, at different angles (they are not parallel), intersect on 1 line.

Answer 2

so would it be 0,1,2 or 3?

Answer 3

sorry the 3rd choice

Answer 4

so 3?

Answer 5

yea

Answer 6

thanks :D

Answer 7

thought i'd id with a visual

Answer 8

aid*

Answer 9

thanks :DDDD