document.write( "Question 1135868: it is given that sin A = K, where A is an angle measured in radians,
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document.write( " and pi < A < (3pi/2)\r
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document.write( "If sin B = k, which of the following is the value of B?\r
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document.write( "A) A - pi
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document.write( "B) pi + A
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document.write( "C) 2pi - A
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document.write( "D) 3pi - A \n" );
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Algebra.Com's Answer #753604 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "The identities I will be using are \n" ); document.write( "sin(A+B) = sin(A)cos(B) + cos(A)sin(B) \n" ); document.write( "and \n" ); document.write( "sin(A-B) = sin(A)cos(B) - cos(A)sin(B)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's the second identity mentioned to expand out choice A like so \n" ); document.write( "sin(A - pi) = sin(A)cos(pi) - cos(A)sin(pi) \n" ); document.write( "sin(A - pi) = sin(A)(-1) - cos(A)(0) \n" ); document.write( "sin(A - pi) = -sin(A) \n" ); document.write( "sin(A - pi) = -K \n" ); document.write( "Choice A is crossed off the list because we want K instead of -K\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Use the first identity to expand out the sine value of choice B \n" ); document.write( "sin(pi+A) = sin(pi)cos(A) + cos(pi)sin(A) \n" ); document.write( "sin(pi+A) = (0)cos(A) + (-1)sin(A) \n" ); document.write( "sin(pi+A) = -sin(A) \n" ); document.write( "sin(pi+A) = -K \n" ); document.write( "we run into the same issue we did in choice A. So choice B is crossed off the list as well.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Go back to the second identity and expand for choice C \n" ); document.write( "sin(2pi - A) = sin(2pi)cos(A) - cos(2pi)sin(A) \n" ); document.write( "sin(2pi - A) = (0)cos(A) - (1)sin(A) \n" ); document.write( "sin(2pi - A) = -sin(A) \n" ); document.write( "sin(2pi - A) = -K \n" ); document.write( "Same issue. Cross choice C off the list.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Repeat for choice D \n" ); document.write( "sin(3pi - A) = sin(3pi)cos(A) - cos(3pi)sin(A) \n" ); document.write( "sin(3pi - A) = (0)cos(A) - (-1)sin(A) \n" ); document.write( "sin(3pi - A) = sin(A) \n" ); document.write( "sin(3pi - A) = K \n" ); document.write( "So this proves that sin(B) = K where B = 3pi-A. We have our answer\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Answer: Choice D) 3pi - A \n" ); document.write( " \n" ); document.write( " |