Question

The idea of Democritus that world is made up of ‘Atomos’ is true even in today’s world. Then,
what do you think could be two possible reasons that people at that time did not accept his theory
instead believed the idea of Aristotle that world is made up of four elements.

Answer 1

Answer:

The length, area and the perimeter of the rectangle are 21cm, 420 cm² and 82 cm respectively.

Step-by-step explanation:

Let the rectangle be ABCD.

According to the question :

➟ Diagonal : BD = 29cm

➟ Breadth : CD = 20cm

All the angles in a rectangle are 90°.

So, ∆BDC is a right angled triangle with ∠BCD = 90°. Using pythagoras theorem :

➟ (P)² + (B)² = (H)²

➟ (BC)² + (20)² = (29)²

➟ BC² + 400 = 841

➟ BC² = 841 – 400

➟ BC² = 441

➟ BC = √441

➟ BC = 21cm

∴ The length of the rectangle BC is 21 cm.

Now, let's find the area of the rectangle :

➟ Area of rectangle = Length × breadth

➟ A = 21cm × 20cm

➟ Area = 420cm²

∴ The area of the rectangle is 420 cm².

Finally, finding the perimeter of the rectangle :

➟ Perimeter = 2 (l + b)

➟ P = 2 (21cm + 20cm)

➟ P = 2 (41cm)

➟ Perimeter = 82cm

∴ The perimeter of the rectangle is 82 cm.

Explanation: