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7.
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Theorem 5.4.7
Let a, b, and c represent the lengths of the three sides of
a triangle, with c the length of the longest side.
1. If c² > a² + b²,
then the triangle is obtuse and the obtuse angle lies opposite the side of length c.
2. If
c² < a² + b², then the triangle is acute.
Determine the type of triangle
represented if the lengths of its sides are as follows: a) 4, 5, 7 b) 6, 7, 8 c) 9, 12,
15 d) 3, 4, 9
What kind of triangle do the figures, at the bottom, represent?
a)
Choosing c = 7, we have 7² > 4² + 5², so the triangle is obtuse. b) Choosing
c = 8, we have 8² < 6² + 7², so the triangle is acute. c) Choosing c = 15,
we have 15² = 9² + 12², so the triangle is a right triangle. d) Because 9 >
3 + 4, no triangle is possible. (Remember that the sum of the lengths of two sides of a
triangle must be greater than the length of the third side.)
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8.
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Please Refer to Unit 5.6
If the ages of the children are 2, 4, and
6 (assume exactness of ages for simplicity) and the total in the account is $7200, then the
amount that each child should receive can be found by solving the equation
Solve this
quation-2x + 4x + 6x = 7200
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