Answer: Choice D) right
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Step-by-step explanation:
If you apply the distance formula, you should find that triangle DEF has the following side lengths
- DE = 5
- EF = 5
- FD = sqrt(50)
Those distances are exact. The sqrt(50) approximates to 7.071
Since 7.071 is the longest side, we'll make c = sqrt(50)
Then we have a = 5 and b = 5
Note that a^2+b^2 = 5^2+5^2 = 50 while c^2 = (sqrt(50))^2 = 50
Both a^2+b^2 and c^2 are equal to 50.
That means a^2+b^2 = c^2 is a true equation for the a,b,c values mentioned.
By the converse of the pythagorean theorem, we have shown that triangle DEF is a right triangle.
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Side notes:
- Triangle DEF is also isosceles because a = b = 5.
- If a^2+b^2 > c^2, then the triangle is acute
- If a^2+b^2 < c^2, then the triangle is obtuse
- If a = b = c, then we have an equiangular triangle