It is known that BD is the middle line of △ ABC, and the perimeter of △ abd is 2cm longer than that of △ BCD. If the perimeter of △ ABC is 18cm and AC = 4cm, the lengths of AB and BC are obtained

∵ BD is the middle line of △ ABC, ∵ ad = CD = 12ac, ∵ abd is 2cm longer than △ BCD, ∵ (AB + AD + BD) - (BD + CD + BC) = ab-bc = 2 ①, ∵ ABC is 18cm in circumference, AC = 4cm, ∵ 4 + AB + BC = 18 ②, simultaneous ① and ② get: ab = 8, BC = 6. So AB is 8cm in length and BC is 6cm in length

Find the document: the perimeter of a rectangle is 150, and when one side is long, X (CM), the functional relationship between the area of the rectangle y square centimeter and (CM) is?

Let the other side be long b, 2 (x + b) = 150, y = x (75-x)

The sum of the width of a rectangle and the side length of a square is 20 cm. The perimeter of a rectangle is one and one-third of its length. The width of a rectangle is four fifths of its length. What is the sum of its length and its area?
The sum of the width of a rectangle and the side length of a square is 20 cm. The perimeter of a square is 1 and 1 / 3 times that of a rectangle. The width of a rectangle is 4 / 5 of its length. What is the sum of the area of a rectangle and a square?

Let the width of the rectangle be x, the length be 5 / 4x, and the length of the square line be y
x+y=20
4y=4/3*(x+5/4x)*2
x=8
y=12
The area of rectangle is 8 * 10 = 80
The area of a square is 12 * 12 = 144

It is known that the circumference of a rectangle is 20 cm. If we increase its length and width by 3 cm each, how much does the circumference of the new rectangle increase and how much does the area increase

Perimeter increase: 3 × 2 × 2 = 12 cm
Area increase: 20 △ 2 × 3 + 3 × 3 = 39 square centimeter

It is known that BD is the middle line of △ ABC, and the perimeter of △ abd is 2cm longer than that of △ BCD. If the perimeter of △ ABC is 18cm and AC = 4cm, the lengths of AB and BC are obtained