SOLUTION: The sides of a triangle have lengths of x,x+4,and 20.If the longest side is 20,Which of the following values of x would make the triangle obtuse A.8 B.10 C.12 D.15 Thank you s

Question 963366: The sides of a triangle have lengths of x,x+4,and 20.If the longest side is 20,Which of the following values of x would make the triangle obtuse
A.8
B.10
C.12
D.15
Thank you stephanie
Answer by CubeyThePenguin(3113) (Show Source): You can put this solution on YOUR website!
x^2 + (x + 4)^2 = 20^2
2x^2 + 8x + 16 = 400
x^2 + 4x + 8 = 200
x^2 + 4x - 192 = 0
(x + 16)(x - 12) = 0

x = 12 for the triangle to be right. Anything less makes it acute and anything more makes it obtuse, so the answer is D.
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