The area of rectangle abcd is 72. if point a and the midpoints of bc and cd are joined to form triangle, the area of that triangle is

  27

Step-by-step explanation:

Name the midpoint of BC point M and the midpoint of CD point N.

Triangle ABM has the 1/4 the area of the rectangle, 18. Triangle ADN also has 1/4 the area of the rectangle, 18. Triangle CMN has 1/8 the area of the rectangle, 9. That is, of the rectangle area, ...

  18 + 18 + 9 = 45

are not included in triangle AMN. So, the area of that triangle is ...

  72 -45 = 27 . . . . units²

Comment on the triangle area

The triangle created by joining the midpoint of the side of a rectangle with an opposite vertex will have the same dimension as the rectangle in one direction (L), and half the dimension of the rectangle in the other direction (W). Thus, where the rectangle area is LW, the triangle area is (1/2)(L)(1/2W) = (1/4)LW, 1/4 the area of the rectangle.

Similarly, if the midpoints of adjacent sides are joined to form a triangle, the area of that is (1/2)(1/2L)(1/2W) = (1/8)LW, or 1/8 the area of the rectangle.

answer: the correct one is a

step-by-step explanation:

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have