Problem 1
Answer: It is possible to draw a triangle
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Explanation:
We use the triangle inequality theorem. Consider a triangle with sides a,b,c
A triangle is only possible if and only if the following three inequalities are all true
Basically, if we can add any two sides to get a sum larger than the third side, then we can form a triangle.
If a = 3, b = 4, and c = 5, then
- a+b = 3+4 = 7 which is indeed larger than c = 5
- b+c = 4+5 = 9 which is larger than a = 3
- a+c = 3+5 = 8 which is larger than b = 4
All three conditions are met, therefore we have a triangle possible.
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Problem 2
Answer: No, a triangle is not possible
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Explanation:
For this problem, and the next two problems, we'll use the triangle inequality theorem also.
Notice that a+b = 4+5 = 9 but this is not larger than c = 9
So the condition a+b > c is not true, and therefore we do not have a triangle possible.
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Problem 3
Answer: No, a triangle is not possible
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Explanation:
Similar to problem 2. A triangle isn't possible because a+b = 5+6 = 11 which is not larger than c = 12.
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Problem 4
Answer: It is possible to draw a triangle
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Explanation:
A triangle is possible here because
- a+b = 3.5+4.5 = 8 which is larger than c = 7
- b+c = 4.5+7 = 11.5 which is larger than a = 3.5
- a+c = 3.5+7 = 10.5 which is larger than b = 4.5
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Problem 5
Answer: a, c, b
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Explanation:
Here are two rules we'll use here
- The smallest angle is always opposite the smallest side
- The largest angle is always opposite the largest side
This applies to triangles only.
From the diagram, we can see that the 28 inch side is the longest. Angle 'a' is opposite this, making angle 'a' to be the largest angle.
Then we see that angle b is opposite the smallest side, so angle b is the smallest angle. Angle c is somewhere in between angles 'a' and b. So that's why we get the order a, c, b when sorting the angles from largest to smallest.
