30/sin^2 38+sin^2 128

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To simplify this expression, we will first use the trigonometric identity:

sin^2(x) = 1 - cos^2(x)

Therefore, sin^2(38) = 1 - cos^2(38)
And sin^2(128) = 1 - cos^2(128)

Now, we can rewrite the expression as:

30/(1 - cos^2(38)) + (1 - cos^2(128))

Multiplying both terms by (1 + cos^2(38)) and (1 + cos^2(128)), we simplify it further:

30 + 30cos^2(38) + (1 + cos^2(128)) - cos^2(128)

Finally, combining like terms, we get:

31 + 30cos^2(38) - cos^2(128)

Therefore, the simplified expression is 31 + 30cos^2(38) - cos^2(128).