document.write( "Question 392042: If tan a=1/5 and tan b=1/239, find the value of tan(4a-b) \n" ); document.write( "
Algebra.Com's Answer #278238 by espeigel(1)\"\" \"About 
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This trig problem involves trig identities and double angle formulas. You should start with
\n" ); document.write( "1. tan (4a - b) = tan4a - tanb / 1 + tan4a tanb
\n" ); document.write( "2. tan4a = 2tan2a / 1-2tan^2 a
\n" ); document.write( "3. tan2a = 2tana / 1- tan^2a
\n" ); document.write( " = 2(1/5) / 1 - (1/25)
\n" ); document.write( " = (2/5) / (24/25)
\n" ); document.write( " = 5/12
\n" ); document.write( "4. tan4a = 2tan2a / 1-2tan^2 a
\n" ); document.write( " = 2(5/12) / (1 - 25/144)
\n" ); document.write( " = (5/6) / (119/144)
\n" ); document.write( " = 120/119
\n" ); document.write( "5. tan (4a - b) = tan4a - tanb / 1 + tan4a tanb
\n" ); document.write( " = (120/119) - (1/239) / 1 + (120/119)(1/239)
\n" ); document.write( " = (28561/28441) / 1 + 120/28441
\n" ); document.write( " = (28561/28441) / (28561/28441)
\n" ); document.write( " = 1 \n" ); document.write( "
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