SOLUTION: The sides of a triangle are x,y and √x^2+y^2 +xy. Find the greatest angle

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Question 1167410: The sides of a triangle are x,y and √x^2+y^2 +xy. Find the greatest angle
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
not clear what's under the radical.

Answer by ikleyn(52767) About Me  (Show Source):
You can put this solution on YOUR website!
.

Apply the cosine law

    x^2 + y^2 - 2xy*cos(a) = x^ 2 + y^2 + xy,

where "a" is the angle between the sides x and y.



It gives, after reducing

    -2xy*cos(a) = xy

     cos(a) = -1%2F2

     a = 2pi%2F3 = 120 degrees.    ANSWER

Solved.