Answer:
7.5 cm
Step-by-step explanation:
Since it's a right triangle, apply pythegorean theorem
Let the missing side be x
[tex] {7.8}^{2} = 2.1 { }^{2} + x {}^{2} [/tex]
[tex]60.84 = 4.41 + {x}^{2} [/tex]
[tex] {x}^{2} = 60.84 - 4.41[/tex]
[tex] {x}^{2} = 56.43[/tex]
[tex] \sqrt{ {x}^{2} } = \sqrt{56.43} [/tex]
[tex]x = 7.5[/tex]
Therefore, the length of the missing side is 7.5 cm
