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Mathematics

Statement 1: A rhombus shaped sheet with perimeter 40 cm has one diagonal 12 cm and the other diagonal is 16 cm.

Statement 2: If the other diagonal of this rhombus = x cm, x = 102 - 62.

  1. Both the statements are true.

  2. Both the statements are false.

  3. Statement 1 is true, and statement 2 is false.

  4. Statement 1 is false, and statement 2 is true.

Mensuration

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Answer

Given,

The perimeter of a rhombus = 40 cm.

One diagonal = 12 cm.

As we know, the perimeter of the rhombus = 4 x side

⇒ 4 x side = 40 cm

⇒ side = 404\dfrac{40}{4} cm

⇒ side = 10 cm

A rhombus shaped sheet with perimeter 40 cm has one diagonal 12 cm and the other diagonal is 16 cm. Area and Perimeter of Plane, Concise Mathematics Solutions ICSE Class 9.

Let ABCD be a rhombus. From figure,

AB = 10 cm

Let diagonal AC = 12 cm

We know that,

Diagonals of rhombus bisect each other.

Then, OA = OC = 122\dfrac{12}{2} = 6 cm

Let OB be a cm.

Since the diagonal of a rhombus bisect at 90°.

Applying pythagoras theorem in triangle AOB, we get:

⇒ AB2 = OA2 + OB2

⇒ (10)2 = (6)2 + a2

⇒ a2 = (10)2 - (6)2

⇒ a2 = 100 - 36

⇒ a2 = 64

⇒ a = 64\sqrt{64}

⇒ a = 8

So, OB = 8 cm

BD = 2 x OB = 2 x 8 cm = 16 cm.

∴ Statement 1 is true.

As solved above,

If the other diagonal of this rhombus = x cm,

Then x2\dfrac{x}{2} will be equal to 102 - 62.

∴ Statement 2 is false.

∴ Statement 1 is true, and statement 2 is false.

Hence, option 3 is the correct option.

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