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Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 8

The area of a rectangle of length 21 cm and diagonal 29 cm is __________ - Mathematics

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Question

The area of a rectangle of length 21 cm and diagonal 29 cm is __________

Options

  • 609 cm2

  • 580 cm2

  • 420 cm2

  • 210 cm2

MCQ
Fill in the Blanks
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Solution

420 cm

Explanation;

Hint:

length = 21 cm

diagonal = 29 cm

By the converse of Pythagoras theorem,

AB2 + BC2 = AC2

212 + x2 = 292

x2 = 841 – 441

400 = 202

x = 20 cm

Now area of the rectangle = length × breadth.

i.e AB × BC

= 21 cm × 20 cm

= 420 cm2

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Converse of Pythagoras Theorem
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Chapter 5: Geometry - Exercise 5.2 [Page 179]

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Samacheer Kalvi Mathematics [English] Class 8 TN Board
Chapter 5 Geometry
Exercise 5.2 | Q 14 | Page 179

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