When two coherent waves undergo destructive interference, the resulting intensity can be calculated as
[tex] I_{new} = I_{1} + I_{2} - 2\sqrt{I_{1}I_{2} [/tex]
where I₁ and I₂ are the given intensities of the waves. Thus, for these two particular coherent waves, we have
[tex] I_{new} = 8.0 + 4.0 - 2\sqrt{(0.8)(0.4)} [/tex]
[tex] I_{new} = 0.69 [/tex]
Thus, the resulting intensity has a value of 0.69 units.
Answer: 0.69 units
