Chapter 3
The World of Numbers
CBSE Class 9
Mathematics Solutions
Educart Mathematics class Class 9 NCERT Exemplar cover
Question:

Find the lengths of the hypotenuses of all the right triangles in the given figure which is referred to as the square root spiral.

Find the lengths of the hypotenuses of all the right triangles in the given figure which is referred to as the square root spiral.

Answer: Verified

In a square-root spiral, start with a right triangle having both legs of length 1. Each new triangle is right-angled, with one leg being the previous hypotenuse and the other leg of length 1.

Triangle 1: legs 1 and

hypotenuse=12+12=2\Rightarrow \text{hypotenuse} = \sqrt{1^2 + 1^2} = \sqrt{2}

Triangle 2: legs 2\sqrt{2} and 1

hypotenuse=2+1=3\Rightarrow \text{hypotenuse} = \sqrt{2+1} = \sqrt{3}

Triangle 3: legs 3\sqrt{3} and 1

hypotenuse=3+1=4=2\Rightarrow \text{hypotenuse} = \sqrt{3+1} = \sqrt{4} = 2

Triangle 4: legs 2 and 1

hypotenuse=4+1=5\Rightarrow \text{hypotenuse} = \sqrt{4+1} = \sqrt{5}

Triangle 5: legs 5\sqrt{5} and 1

hypotenuse=6\Rightarrow \text{hypotenuse} = \sqrt{6}

Triangle 6: legs 6\sqrt{6} and 1

hypotenuse=7\Rightarrow \text{hypotenuse} = \sqrt{7}

Triangle 7: legs 7\sqrt{7} and 1

hypotenuse=8=22\Rightarrow \text{hypotenuse} = \sqrt{8} = 2\sqrt{2}

Triangle 8: legs 8\sqrt{8} and 1

hypotenuse=9=3\Rightarrow \text{hypotenuse} = \sqrt{9} = 3

Triangle 9: legs 3 and 1

hypotenuse=10\Rightarrow \text{hypotenuse} = \sqrt{10}

Triangle 10: legs 10\sqrt{10} and 1

hypotenuse=11\Rightarrow \text{hypotenuse} = \sqrt{11}

Concept Applied

In a square-root spiral, the length of each new hypotenuse is found using the Baudhāyana-Pythagoras theorem, giving 2,3,4,5\sqrt{2}, \sqrt{3}, \sqrt{4}, \sqrt{5}, and so on.

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