हिंदी

The perimeter of the rectangle whose length is 60 cm and a diagonal is 61 cm is ______. - Mathematics

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प्रश्न

The perimeter of the rectangle whose length is 60 cm and a diagonal is 61 cm is ______.

विकल्प

  • 120 cm

  • 122 cm

  • 71 cm

  • 142 cm

MCQ
रिक्त स्थान भरें

उत्तर

The perimeter of the rectangle whose length is 60 cm and a diagonal is 61 cm is 142 cm.

Explanation:


Consider the rectangle PQRS,

Given, length of rectangle PQ = 60 cm, Diagonal of the rectangle = 61 cm.

To find out the height of the rectangle, consider the right angled triangle PQR.

From the Pythagoras theorem, PR2 = PQ2 + RQ2

⇒ 612 = 602 + RQ2

⇒ 3721 = 3600 + RQ2

⇒ RQ2 = 3721 – 3600

⇒ RQ2 = 121

⇒ RQ = `sqrt(121)`

⇒ RQ = 11 cm

Then, the perimeter of the rectangle PQRS = 2(Length + Breadth)

= 2(60 + 11)

= 2(71)

= 142 cm

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अध्याय 6: Triangles - Exercise [पृष्ठ १६१]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 7
अध्याय 6 Triangles
Exercise | Q 16. | पृष्ठ १६१

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