Page 167 - NUMINO Challenge_D1

Answer
Key

Creative Thinking p.126~p.127 15 AnglesandTime p.128~p.129

1 Example 90 17.5
90 , 17.5 , 72.5

2 The area of the rectangle is 25 16 400 cm2. TryItAgain If the hour hand points to 6 and the minute
hand points to 8, the angle that is
Therefore, each side of the square is 20 cm formed by the hands is 60 . Since the hour
hand moves 20 in 40 minutes, the angle
long. formed by the hands is 60 20 40 .

5 cm 5 cm 4 cm Example 11 11, 65 5 65 5 , 7, 5 5
5 cm 4 cm 11 11 11
5 cm 4 cm 5 cm 4 cm
5 cm 4 cm 5 cm 4 cm TryItAgain The hour and minute hands overlap at
5 cm 4 cm 5 cm 4 cm 5
4 cm 11
Answers will vary.
regular intervals: 720 11 65 minutes.

The two hands overlap at 12 o'clock,

3 You can draw a square on the U-shaped between 1 and 2 o'clock, and between 2

pentomino and find parts that can be divided and 3 o'clock.

into four pieces. Therefore, 12 65 5 65 5 2 : 10 10 .
11 11 11

Type 15-1 Finding the Time p.130~p.131

Answers will vary. 1 360 12 30
2 30 80 110
4 Since the total area is 81 cm2, you can make a 3 110 5.5 20 minutes
3 1 : 20
square with sides 9 cm long. You can divide the
figure into three different pieces as shown
below, and put the pieces together to make a
square.

Answers will vary.

NUMINO Challenge D1