Question

Find the side cube is 9 cm what will be the diagonal of the cube in cm​

Answer 1

let cube be ABCD

as AB= BC= 9cm

we can use phythagoras theorem

AB^2 + BC^2 = CA^2

9^2 +9^2 = CA^2

81+81= CA^2

CA=12.7

Answer 2

$\orange{side = 9 \: cm} \\ \\ \green{let \: the \: diagonal \: ac = x} \\ \\ \pink{applying \: pgt \: triangle \: abc } \\ \\ \blue{ {x}^{2} = {9}^{2} + {9}^{2} }\\ \\ \blue{ {x}^{2} = 81 + 81} \\ \\ \blue{x = \sqrt{162} } \\ \\ \red{x = 9 \sqrt{2} }$