document.write( "Question 33076: abc is a triangle in which ab = 12 cm , ca = 13cm , c b = 5 cm find m (< abc ) \n" ); document.write( "

Algebra.Com's Answer #20292 by kietra(57) $\"\"$ $\"About$

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ab = 12 cm , ca = 13cm , c b = 5 cm To find m (< abc, you must use the cosine rule. You can use the cosine rule when you are given two sides and the included angle or when you are given three sides. \r
\n" ); document.write( "\n" ); document.write( "cosB = (a^2 + c^2 - b^2)/2ac
\n" ); document.write( "cosB = (5^2 + 12^2 - 13^2)/2*5*12
\n" ); document.write( "cosB = (25 + 144 - 169)/120
\n" ); document.write( "cosB = (169 - 169)/120
\n" ); document.write( "cosB = 0/120 = 0
\n" ); document.write( "B = cos^-1(0)
\n" ); document.write( "B = 90 degrees
\n" ); document.write( "is there any other help we tutors can help with?\r
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