A triangle has sides A, B, and C. Sides A and B are of lengths #5# and #8#, respectively, and the angle between A and B is #pi/3#. What is the length of side C?

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Answer 1 · 2017-09-13T10:55:45

The length of side #C# is #7# unit.

Sides of triangle are #A= 5 ,B=8#

The angle between #A and B# is #/_c = pi/3=180/3=60^0#

Applying cosine law we can find #C#

#C= sqrt(A^2+B^2-2AB cosc) # or

#C= sqrt(5^2+8^2-2*5*8 cos60) # or

#C= sqrt(25+64-80 * 1/2) # or

#C= sqrt(25+64-40) = sqrt49 =7# unit

The length of side #C# is #7# unit . [Ans]