The length of a diagonal of square is 20cm.

a) Find the length of a side of the square.

b) Show that the area of the square is 200cm²

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[tex]\bold{\huge{\underline{ Solutions }}}[/tex]

Given :-

  • The length of a diagonal is 20 cm

To Find and prove :

  • We have to find the length of a side of the square
  • We also have to show that the area of square is 200 cm²

Solution ( a)

We have,

  • The length of the diagonal of a square is 20 cm

We know that,

[tex]\bold{\red{ d = }}{\bold{\red{\sqrt{2}}}}{\bold{\red{ a }}}[/tex]

  • Where, a is the length of the side of the square
  • d is the the length of the diagonal

Subsitute the required values in the above formula :-

[tex]\sf{ 20 = }{\sf{\sqrt{2}}}{\sf{ a }}[/tex]

Squaring on both the sides :-

[tex]\sf{ 400 = 2a^{2}}[/tex]

[tex]\sf{\dfrac{400}{2}}{\sf{ = a^{2}}}[/tex]

[tex]\sf{ 200 = a^{2}}[/tex]

[tex]\bold{ a = 14.14 cm }[/tex]

Hence, The side of the square is 14.14 cm

Solution ( b) :-

Here, we have to prove that,

  • The area of square is 200 cm²

We know that,

Area of square

[tex]\bold{\pink{ = side}}{\bold{\pink{\times{ side}}}}[/tex]

  • The side of the square is 14.14 cm

Subsitute the required values,

[tex]\sf{ = 14.14 }{\sf{\times{ 14.14}}}[/tex]

[tex]\bold{ = 200 cm^{2}}[/tex]

Hence, It is proved that the area of the square is 200 cm².