1,3 1,3 1,4

The circumference is increased by 8 cm, and the area is doubled.

By analogy, training 2

Perimeter: 18+24+30 = 72cm Perimeter:14+10+22+15.5 = 61.5cm.

Area: 18×24÷2=2 16 cm2 Area: (22+14) ÷ 2×10 =180cm2.

By analogy, training 3

(8×8-4×4)÷4=8

6×6-(3×2÷2+3×6÷2+4×6÷2)= 12

( 10+8÷2+ 10)÷ 10=5

By analogy, training 4

4×2=8 8×3=24 24+8+4=36

6×4=24 6÷3=2 24+2+6=32

20×20+ 10× 10-20×20÷2-20× 10÷2=200

spraying jet

A set of parallel and equal opposite sides

12 4

40 40 obtuse angle

20 24 25 square meters

48

Forty-four

50

54 15

Two:

Washington D.C.

3: 3× 2.5 ÷ 2 = 3.75 16× 7 ÷ 2 = 565× 5+4× 4-(5+2) ÷ 2× (5+4) = 9.5

Time is running out. Let's enter the answer below.

Four: (1)30 (2)4

V: (1) 41.25 (2)12 (3) 50000 (4) 6561(5)157.

Interesting topic:

13+35+49=97