Which classification best represents a triangle with side lengths [tex]\(6 \text{ cm}, 10 \text{ cm},\)[/tex] and [tex]\(12 \text{ cm}?\)[/tex]

A. Acute, because [tex]\(6^2 + 10^2 \ \textless \ 12^2\)[/tex]

B. Acute, because [tex]\(6 + 10 \ \textgreater \ 12\)[/tex]

C. Obtuse, because [tex]\(6^2 + 10^2 \ \textless \ 12^2\)[/tex]

D. Obtuse, because [tex]\(6 + 10 \ \textgreater \ 12\)[/tex]



Answer :

Let's classify the triangle with the side lengths [tex]\( 6 \, \text{cm} \)[/tex], [tex]\( 10 \, \text{cm} \)[/tex], and [tex]\( 12 \, \text{cm} \)[/tex].

### Step 1: Calculate the squares of each side:
- For side [tex]\( a = 6 \)[/tex]:
[tex]\[ a^2 = 6^2 = 36 \][/tex]

- For side [tex]\( b = 10 \)[/tex]:
[tex]\[ b^2 = 10^2 = 100 \][/tex]

- For side [tex]\( c = 12 \)[/tex]:
[tex]\[ c^2 = 12^2 = 144 \][/tex]

Now, we have:
[tex]\[ a^2 = 36, \quad b^2 = 100, \quad c^2 = 144 \][/tex]

### Step 2: Sum of squares of the two smaller sides:
[tex]\[ a^2 + b^2 = 36 + 100 = 136 \][/tex]

### Step 3: Compare the sum of the squares with the square of the largest side:
We see that:
[tex]\[ a^2 + b^2 < c^2 \quad \text{(since } 136 < 144 \text{)} \][/tex]

### Step 4: Conclusion based on the comparison:
- If [tex]\( a^2 + b^2 > c^2 \)[/tex], the triangle is acute.
- If [tex]\( a^2 + b^2 = c^2 \)[/tex], the triangle is right-angled.
- If [tex]\( a^2 + b^2 < c^2 \)[/tex], the triangle is obtuse.

Since [tex]\( 136 < 144 \)[/tex], we conclude that the triangle is obtuse.

Thus, the classification that best represents the triangle with side lengths [tex]\( 6 \, \text{cm} \)[/tex], [tex]\( 10 \, \text{cm} \)[/tex], and [tex]\( 12 \, \text{cm} \)[/tex] is:

[tex]\[ \boxed{\text{obtuse, because } 6^2 + 10^2 < 12^2} \][/tex]

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