What is the halving and doubling strategy

What is the length of the missing leg in this right triangle? 18 mm 24 mm 26 mm 32 mm

(01.02 lc) angle abc has point e on ray ba and point d on ray bc. points e and d are equidistant from point b. to bisect angle abc, which of the following needs to be identified for the construction? the distance between points e and d the point in the angle that is equidistant from points e and d the endpoint of rays ba and bc the point outside of the angle that is equidistant from points e and d

Kayla wants to find the width, ab, of a river. she walks along the edge of the river 65 ft and marks point c. then she walks 25 ft further and marks point d. she turns 90° and walks until her location, point a, and point c are collinear. she marks point e at this location, as shown. (a) can kayla conclude that δ and δ are similar? why or why not? (b) suppose de = 15 ft. what can kayla conclude about the width of the river?