Step 1 :Given the expression is \(\csc ^{2}\left(225^{\circ}\right)+\cos ^{2}\left(120^{\circ}\right)\).
Step 2 :Recall that the cosecant function is the reciprocal of the sine function. So, \(\csc ^{2}\left(225^{\circ}\right)\) is equivalent to \(1/\sin ^{2}\left(225^{\circ}\right)\).
Step 3 :We need to calculate the sine of 225 degrees and the cosine of 120 degrees, square them, and add the results.
Step 4 :\(\sin ^{2}\left(225^{\circ}\right)\) is approximately 0.5 and \(\cos ^{2}\left(120^{\circ}\right)\) is approximately 0.25.
Step 5 :Adding these results gives 2.25.
Step 6 :Final Answer: The exact value of \(\csc ^{2}\left(225^{\circ}\right)+\cos ^{2}\left(120^{\circ}\right)\) is \(\boxed{\frac{9}{4}}\).