Page 166 - NUMINO Challenge_C1

Problem solving 3 Divide the square into triangles of the same

1 Divide the shape into two triangles and two shape and size. Compare the areas of the colored

trapezoids. regions.

(5 2 1 ) (5 2) 2 1 (4 2 1 ) AB
2 22
In A and B, each has six colored smaller triangles.
Therefore, the area of B is the same as A, which is
12 cm2.

(6 2) 4 1 32 cm2 4 A
2
E
2 Subtract four triangles from the square. F C
B

(4 4) {(1 3 1 ) (1 1 1 ) (2 3 1) D
22 2
The length of side BE is twice the length of side
(2 1 1 )} 16 6 10 cm2 BC. So if you connect the middle of side BE
2 (point F) with point A, triangles , , all have
the same base, height, and therefore the same
Creative Thinking p.118~p.119 area. Triangles , , , which are formed by
connecting points B, F, D, all have the same base,
1 If you rotate the triangle, the colored region is height and area as well. Also if you look at
triangles and , side AC and side CD are of
as shown below. Since the area of the colored the same length and height, so the area is the
region is 36, the area of one same. Therefore, all six triangles have the same
triangle of medium size is area, so the area of triangle ADE is
36 3 12. This triangle is 10 6 60 cm2.
made up of 4 smaller
triangles, so the area of
each small triangle is 12 4 3.

2 8 cm2 10.5 cm2 8.5 cm2
7.5 cm2 6.5 cm2
8 cm2

Answer Key