A bookmark has an area of 21 square centimeters. Its perimeter is 20 centimeters. What are the dimensions of the bookmark?

The dimensions are 7cm and 3cm.

Step-by-step explanation:

The following equation can be deduced from the question

L × W = 21 i

2L + 2W = 20 ii

Divide equation ii through by 2

(2L + 2W = 20) / 2

L + W = 10 iii

From equation iii

L = 10 - W iv

Put equation iv into I

L × W = 21

(10 - W) × W = 21

10W - W² = 21

W² - 10W + 21 = 0

W² - 7W - 3W + 21 = 0

W(W - 7) - 3(W - 7) = 0

W - 3 = 0

W = 0+3

W = 3 centimeter

Since,

Length × Width = 21

Length = 21/3

Length = 7 centimeters

The dimensions are 7cm and 3cm.

for any of you who need the translation here it is

step-by-step explanation:

find the angular size of the equatorial radius of the earth, if the horizontal parallax of the sun

21/58.

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