Mathematics: Which of these describes a unique polygon? A quadrilateral with 3 sides lengths 5 inches long A triangle with a side length of 6 inches, 7 inches, and 8 inches A triangle with angles 30, 60, and 90 A triangle with side lengths 5 cm and 4 cm and a 70 angle

Which of these describes a unique polygon? A quadrilateral

dolphin5836

05.05.2021

It can't be expressed in that form

Step-by-step explanation:

From difference of two squares:

${ \boxed{(a + b)(a - b) = ( {a}^{2} - {b}^{2} )}}$

a » 9

b » 2i

$(9 + 2i)(9 - 2i) = \{ {(9)}^{2} - {(2i)}^{2} \} \\ \\ = (81 - 4 {i}^{2} )$

but i² is -1 [ complex numbers ]

$= \{81 - 4( - 1) \} \\ = 81 + 4 \\ = 85$

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