BA LLB Banaras Hindu University 2019 Solved Paper

Question : 124 of 170

Marks: +1, -0

The adjoining figures shows a set of concentric squares. If the diagonal of the innermost square is 2 unit and if the distance between the corresponding corners of any two successive squares is 1 unit, find the difference between the areas of the eight and the seventh squares, counting from the innermost square.

$10.2$ sq unit
30 sq unit
$35.2$ sq unit
None of the above

Validate

Solution:

The diagonal of the innermost square is 2 unit. The diagonal of every successive square would increases by 2 unit (since corners are one unit apart). So, the diagonal of the 7 th square

=14

and that of the 8 th square

=16

. Area of the 7 th square

=\;{1}/{2}, 14^{2}

and that of 8 th square

=\;{1}/{2} ⋅ 16^{2}

i.e. 98 and 128 respectively.
Hence, the difference in their areas

=(128-98)=30

sq unit

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