document.write( "Question 1152666: If sin^2 (𝛑/9) + sin^2 (2𝛑/9) + sin^2 (3𝛑/9) + sin^2 (4𝛑/9) = 9/4,
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Algebra.Com's Answer #774722 by ikleyn(52943) $\"\"$ $\"About$

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document.write( "cos^2 (𝛑/9)         + cos^2 (2𝛑/9)       + cos^2 (3𝛑/9)       + cos^2 (4𝛑/9) = \r\n" );
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document.write( "= (1 - sin^2 (𝛑/9)) + (1 - sin^2 (2𝛑/9)) + (1 - sin^2 (3𝛑/9)) + (1 - sin^2 (4𝛑/9)) = \r\n" );
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document.write( "= 4 - (sin^2 (𝛑/9) + sin^2 (2𝛑/9) + sin^2 (3𝛑/9) + sin^2 (4𝛑/9)) =  =  = .    ANSWER\r\n" );
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