The crow stared at the screen, as it had many times before. Six shapes appeared. Five were neat, balanced, regular; one was ...

The techniques used are useful for solving all kinds of other geometry problems too ... That's these two. Second, angles on a straight line add up to 180 degrees. Using these two rules it's ...

Managing a crowd [efficiently]—in train situations, concerts, even in the streets—is very important” for safety and city ...