(1) B (-6, o) draws a vertical line from point b to point f on the X axis to form an isosceles right triangle BCF, and then calculates the distance of CF according to Pythagorean theorem, so it can be clear at a glance.

(2) We know from the title: e (0 0,4). According to Pythagorean theorem, we can find the length, bisector,,, and coordinates of point D, and then bring it into the formula to find the analytical formula of DE.