document.write( "Question 343975: In triangle ABC, C = 60 degrees, a = 12, and b= 5. Find c.\r
\n" ); document.write( "\n" ); document.write( "a. 109.0
\n" ); document.write( "b. 10.4
\n" ); document.write( "c. 11.8
\n" ); document.write( "d. 15.1
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Algebra.Com's Answer #246087 by CharlesG2(834)\"\" \"About 
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In triangle ABC, C = 60 degrees, a = 12, and b= 5. Find c.
\n" ); document.write( "a. 109.0
\n" ); document.write( "b. 10.4
\n" ); document.write( "c. 11.8
\n" ); document.write( "d. 15.1\r
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\n" ); document.write( "\n" ); document.write( "are a and b 2 of the sides?\r
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\n" ); document.write( "\n" ); document.write( "is c one of the sides?\r
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\n" ); document.write( "\n" ); document.write( "is this a right triangle?\r
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\n" ); document.write( "\n" ); document.write( "maybe you should repost\r
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\n" ); document.write( "\n" ); document.write( "if this is right triangle:
\n" ); document.write( "then angles would be 30-60-90,
\n" ); document.write( "angle C would be the 60, angle B would be the 30, angle A would be the 90,
\n" ); document.write( "side c opposite angle C, side b = 5, side a = 12
\n" ); document.write( "pythagorean theorem: b^2 + c^2 = a^2 --> 5^2 + c^2 = 12^2
\n" ); document.write( "b^2 + c^2 = a^2 --> 5^2 + c^2 = 12^2 = c^2 + 25 = 144
\n" ); document.write( "c^2 = 119
\n" ); document.write( "c = sqrt(119) = 10.9087 to 4 places\r
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\n" ); document.write( "\n" ); document.write( "if this is not a right triangle:
\n" ); document.write( "if angle C of 60 is the side opposite, and a and b are the 2 known sides:
\n" ); document.write( "use law of cosines: c^2 = a^2 + b^2 - 2abcosC
\n" ); document.write( "c^2 = 12^2 + 5^2 - 2 * 12 * 5 * cos 60
\n" ); document.write( "c^2 = 144 + 25 - 120cos60
\n" ); document.write( "c^2 = 169 - 120 * 0.5
\n" ); document.write( "c^2 = 169 - 60 = 109
\n" ); document.write( "c = sqrt(109) = 10.4403 rounded to 4 places
\n" ); document.write( "well this would match up with answer b. 10.4\r
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