Page 189 - NUMINO TB_4B

c. Unit 25. Magic Parentheses

P. 82~83

1+2+ 3 6
1+2 3 24
1 2+ 3 15

Challenge P. 80~81 1+ 2+ 3+ 4 5 51
1+ 2+ 3 4+ 5 42
1 . b . The diameter of the small circle is 6 cm. 1 2 3+ 4+ 5 132

So the radius of the small circle is 3 cm.

Activity 1 P. 84~86

3 cm 3 cm The radius of the 1 . a. 34 8 12 30 b . 26 (12 5) 9
large circle is 6 cm.
42 17
30 9

c . The circle on the left has a diameter of c . 71, 17 d . 15, 4

10 cm. So the radius is 5 cm, and the e . 53 f . 20
g . 21 h . 14
circle on the left and the circle on the right

have the same radius.

2 . c. 45 27 14 32, 32 people

5 cm 5 cm 5 cm d . 40 13 15) 12, 12 erasers
A
B 3 . Sample Answer

Therefore, the length of AB is 5 5 5, 50 10 7 47
which is 15 cm.
Ryan had 50 colored pencils. He lost
c . The circle farthest to the left has a diameter 10 of his colored pencils during the art
class, but then later found 7 of his
of 8 cm. So the radius is 4 cm. All the circle colored pencils. How many colored
are identical, and have the same radius. pencils does he have now?

47 colored pencils

Activity 2 P. 86~87

4 cm 4 cm 4 cm 4 cm 4 cm 1 . a. 45 9 4 20 b . 22 (4 2) 4
A B
5 8
20 4

Therefore, the length of AB is
4 4 4 4 4, which is 20 cm.

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