80 Avant de faire fabriquer un objet en bois, un designer confectionne une maquette à
l'échelle 1/50. Cette maquette a un volume
de 100 cm3
Sachant que la masse volumique du bois uti-
lisé est de 0,9 kg/dm3, quelle est la masse de
l'objet en réalité ?

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?