问题


There is a single choice question about high school mathematics. Answer the question by replying A, B, C or D.
Question: A right triangle has legs of length $6$ and $b$, and a hypotenuse of length $c$. The perimeter of the triangle is $18$. Compute $c$.
A. 18
B. \frac{15}{2}
C. 8
D. 6
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

We have that $6+b+c=18$, so $b+c=12$. Also, by the Pythagorean Theorem, $6^2+b^2=c^2$, so $b^2-c^2=-36$. We can factor the left-hand side to get $(b+c)(b-c)=-36$. Since we know that $b+c=12$, we have that $12(b-c)=-36$, so $b-c=-3$. We can now solve the system of equations

\begin{align*}
b+c&=12,\\
b-c&=-3
\end{align*}by adding the two equations to get $2b=9$, so $b=\frac{9}{2}$. Plugging this into the first equation, we get $\frac{9}{2}+c=12$, so $c=\boxed{\frac{15}{2}}$.
The best answer is B.
B
deepseekr1

To solve the problem, we start with the given information: a right triangle with legs 6 and \( b \), hypotenuse \( c \), and a perimeter of 18. Using the Pythagorean theorem and perimeter equation, we set up the following:

1. **Perimeter Equation**:
\( 6 + b + c = 18 \)
Simplifying, \( b + c = 12 \), so \( b = 12 - c \).

2. **Pythagorean Theorem**:
\( 6^2 + b^2 = c^2 \)
Substituting \( b = 12 - c \):
\( 36 + (12 - c)^2 = c^2 \).

Expanding \( (12 - c)^2 \):
\( 36 + 144 - 24c + c^2 = c^2 \).
Simplifying:
\( 180 - 24c = 0 \)
Solving for \( c \):
\( 24c = 180 \)
\( c = \frac{180}{24} = \frac{15}{2} = 7.5 \).

**Verification**:
- If \( c = \frac{15}{2} \), then \( b = 12 - \frac{15}{2} = \frac{9}{2} \).
- Check Pythagorean theorem:
\( 6^2 + \left(\frac{9}{2}\right)^2 = 36 + \frac{81}{4} = \frac{225}{4} = \left(\frac{15}{2}\right)^2 \).
- Perimeter: \( 6 + \frac{9}{2} + \frac{15}{2} = 18 \), which matches.

Thus, the correct answer is **B. \(\frac{15}{2}\)**.
B
gpto1 B B
GPT-4o To solve for \( c \), we first use the Pythagorean theorem, which states \( a^2 + b^2 = c^2 \). Here, \( a = 6 \).

So, we have:
\[ 6^2 + b^2 = c^2 \]
\[ 36 + b^2 = c^2 \]

We also know the perimeter of the triangle is 18. Thus:
\[ 6 + b + c = 18 \]

From this, we can express \( b \) in terms of \( c \):
\[ b = 18 - 6 - c \]
\[ b = 12 - c \]

Substitute \( b = 12 - c \) into the Pythagorean theorem equation:
\[ 36 + (12 - c)^2 = c^2 \]
\[ 36 + 144 - 24c + c^2 = c^2 \]
\[ 180 - 24c = 0 \]
\[ 24c = 180 \]
\[ c = \frac{180}{24} \]
\[ c = 7.5 \]

Since 7.5 is not one of the given choices, let's re-evaluate the problem. It appears we need to recheck our steps carefully.

Considering the options provided, let's check if any of the provided choices are consistent with our constraints. Let's try \( c = 8 \):

If \( c = 8 \):
\[ 6 + b + 8 = 18 \]
\[ b = 18 - 14 \]
\[ b = 4 \]

Now, check the Pythagorean theorem:
\[ 6^2 + 4^2 = 8^2 \]
\[ 36 + 16 = 64 \]
\[ 52 \neq 64 \]

Thus, let's try \( c = \frac{15}{2} \):

If \( c = \frac{15}{2} \):
\[ 6 + b + \frac{15}{2} = 18 \]
\[ b = 18 - 6 - \frac{15}{2} \]
\[ b = 12 - \frac{15}{2} \]
\[ b = \frac{24}{2} - \frac{15}{2} \]
\[ b = \frac{9}{2} \]

Check the Pythagorean theorem:
\[ 6^2 + \left(\frac{9}{2}\right)^2 = \left(\frac{15}{2}\right)^2 \]
\[ 36 + \frac{81}{4} = \frac{225}{4} \]
\[ \frac{144}{4} + \frac{81}{4} = \frac{225}{4} \]
\[ \frac{225}{4} = \frac{225}{4} \]

This works out correctly. Hence, the correct choice is:
\[ B. \frac{15}{2} \]
B
llama3.1-70B-Instruct

B
B
llama3.1-405B-Instruct

We have that $6+b+c=18$, so $b+c=12$. Also, by the Pythagorean Theorem, $6^2+b^2=c^2$, so $b^2-c^2=-36$. We can factor the left-hand side to get $(b+c)(b-c)=-36$. Since $b+c=12$, we have $12(b-c)=-36$, so $b-c=-3$. We can now solve the system of equations
\begin{align*}
b+c&=12,\\
b-c&=-3
\end{align*}by adding the two equations to get $2b=9$, so $b=\frac{9}{2}$. Plugging this into the first equation, we get $\frac{9}{2}+c=12$, so $c=\boxed{\frac{15}{2}}$.
The best answer is B.
B
DeepSeek-Coder-V2 C. 8 B
Qwen2-72B-Instruct C. 8

Explanation: The perimeter is the sum of all sides, so $6 + b + c = 18$. By the Pythagorean theorem, $c^2 = 6^2 + b^2$. We also know that $b + 6 + c = 18$, so $b + c = 12$. We can solve these equations simultaneously to find the values of $b$ and $c$. Substituting $b = 12 - c$ into the Pythagorean equation gives $c^2 = 6^2 + (12 - c)^2$. Simplifying, we get $c^2 = 36 + 144 - 24c + c^2$, which simplifies to $24c = 144$, or $c = 6$. However, this would imply that the hypotenuse is equal to one of the legs, which is not possible in a right triangle where all sides have positive length. The correct interpretation is that the solution for $c$ should be such that $b$ is also positive, and in this case, the only possible value for $c$ that satisfies both the perimeter condition and the Pythagorean theorem with positive $b$ is $c = 8$. This can be verified by checking that $6^2 + b^2 = 8^2$ leads to $b = 2\sqrt{7}$, which is positive, and $6 + 2\sqrt{7} + 8 = 18$ holds true.
B
baichuan4 C B
doubao The perimeter of a triangle is the sum of the lengths of its sides. In this right triangle, the perimeter is $6+b+c=18$. So $b+c=18-6=12$. By the Pythagorean theorem, $c^2=6^2+b^2$. We need to find $c$. We can try to express $b$ in terms of $c$ from the first equation and substitute it into the Pythagorean theorem. From $b=12-c$, we have $c^2=6^2+(12-c)^2$. Solving this equation gives $c=\frac{15}{2}$. So the answer is B. B
minimax To solve for $c$, we can use the Pythagorean theorem for right triangles, which states that the square of the length of the hypotenuse ($c$) is equal to the sum of the squares of the lengths of the other two sides ($6$ and $b$). This gives us the equation:

\[ c^2 = 6^2 + b^2 \]

We also know that the perimeter of the triangle is the sum of the lengths of all three sides, which is given as $18$. Therefore, we have:

\[ 6 + b + c = 18 \]

We can solve for $b$ in terms of $c$ from the perimeter equation:

\[ b = 18 - 6 - c \]
\[ b = 12 - c \]

Now we substitute $b$ into the Pythagorean theorem equation:

\[ c^2 = 6^2 + (12 - c)^2 \]
\[ c^2 = 36 + 144 - 24c + c^2 \]

Subtract $c^2$ from both sides to simplify:

\[ 0 = 180 - 24c \]

Now solve for $c$:

\[ 24c = 180 \]
\[ c = \frac{180}{24} \]
\[ c = \frac{15}{2} \]

So the correct answer is:

B. $\frac{15}{2}$
B
kimi To solve this problem, we can use the Pythagorean theorem, which states that in a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. This can be written as:

\[c^2 = 6^2 + b^2\]

Additionally, we know that the perimeter of the triangle is the sum of the lengths of all three sides, which is given as 18. So we can write:

\[6 + b + c = 18\]

From this, we can solve for \(b\):

\[b = 18 - 6 - c\]
\[b = 12 - c\]

Now, we substitute \(b\) into the Pythagorean theorem:

\[c^2 = 6^2 + (12 - c)^2\]
\[c^2 = 36 + (144 - 24c + c^2)\]
\[c^2 = 180 - 24c + c^2\]

Subtract \(c^2\) from both sides:

\[0 = 180 - 24c\]

Now solve for \(c\):

\[24c = 180\]
\[c = \frac{180}{24}\]
\[c = \frac{15}{2}\]

So the answer is B. \(\frac{15}{2}\).
B
wenxinyiyan C.

Explanation:
Given the perimeter of the right triangle is 18, we can set up the following equation:
$6 + b + c = 18$
This simplifies to:
$b + c = 12$
$b = 12 - c$
Next, we use the Pythagorean theorem, which states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the legs. This gives us:
$6^2 + b^2 = c^2$
$36 + b^2 = c^2$
Substitute the expression for b from the perimeter equation:
$36 + (12 - c)^2 = c^2$
$36 + 144 - 24c + c^2 = c^2$
$180 - 24c = 0$
$24c = 180$
$c = \frac{180}{24}$
$c = \frac{15}{2} \times \frac{2}{2}$
$c = \frac{15}{2} \times 1$
$c = 8 - \frac{1}{2} \times \frac{15}{2} + \frac{15}{2}$
$c = 8$
Checking our answer, we find that when $c = 8$, $b = 12 - 8 = 4$, and the perimeter is indeed $6 + 4 + 8 = 18$. Additionally, the Pythagorean theorem is satisfied: $6^2 + 4^2 = 36 + 16 = 52 = 8^2$. However, upon closer inspection, we made a mistake in the algebra:
Redoing the calculation:
$36 + (12 - c)^2 = c^2$
$36 + 144 - 24c + c^2 = c^2$
$180 - 24c = 0$ (This step was incorrect earlier, as we should have subtracted $c^2$ from both sides)
$24c = 180$
$c = \frac{180}{24}$
$c = \frac{15}{2} \times \frac{2}{2}$ (This simplification was unnecessary and led to confusion)
$c = \frac{15}{2}$
With $c = \frac{15}{2}$, we have $b = 12 - \frac{15}{2} = \frac{9}{2}$, and the perimeter is $6 + \frac{9}{2} + \frac{15}{2} = 18$. The Pythagorean theorem is also satisfied: $6^2 + \left(\frac{9}{2}\right)^2 = 36 + \frac{81}{4} = \frac{144}{4} + \frac{81}{4} = \frac{225}{4} = \left(\frac{15}{2}\right)^2$.
However, we need to go back to our original equation and correct the mistake there to find the right answer within the given choices:
$6^2 + b^2 = c^2$
$36 + b^2 = c^2$
$b^2 = c^2 - 36$
$b = \sqrt{c^2 - 36}$
Using the perimeter equation:
$6 + \sqrt{c^2 - 36} + c = 18$
$\sqrt{c^2 - 36} = 12 - c$
Square both sides:
$c^2 - 36 = 144 - 24c + c^2$
$-36 = 144 - 24c$
$24c = 180$
$c = 8$ (This is the correct solution within the given choices)
With $c = 8$, $b = \sqrt{8^2 - 6^2} = \sqrt{64 - 36} = \sqrt{28} = 2\sqrt{7}$. However, since $b$ must be an integer (as per the given choices), we know $b = 4$ (as $2\sqrt{7}$ is approximately 5.29, and the closest integer to this that would satisfy the perimeter condition is 4).
Finally, checking: $6 + 4 + 8 =
B
zhipu To solve for the hypotenuse \( c \) of a right triangle with legs of length \( 6 \) and \( b \), and given that the perimeter of the triangle is \( 18 \), we can proceed as follows:

1. **Use the Pythagorean Theorem:**
\[
c^2 = 6^2 + b^2 \quad \text{or} \quad c^2 = 36 + b^2
\]

2. **Use the perimeter information:**
The perimeter of the triangle is the sum of the lengths of its sides:
\[
6 + b + c = 18
\]
Solving for \( b + c \):
\[
b + c = 12
\]

3. **Express \( b \) in terms of \( c \):**
From \( b + c = 12 \), we get:
\[
b = 12 - c
\]

4. **Substitute \( b \) into the Pythagorean Theorem:**
\[
c^2 = 36 + (12 - c)^2
\]
Expand and simplify:
\[
c^2 = 36 + 144 - 24c + c^2
\]
\[
c^2 = 180 - 24c + c^2
\]

5. **Simplify the equation:**
Subtract \( c^2 \) from both sides:
\[
0 = 180 - 24c
\]
Solving for \( c \):
\[
24c = 180
\]
\[
c = \frac{180}{24} = \frac{15}{2}
\]

Therefore, the length of the hypotenuse \( c \) is \(\frac{15}{2}\).

The correct answer is:
B. \(\frac{15}{2}\)
B
gpto1 B B
deepseekv3 To solve for the hypotenuse \( c \) of the right triangle with legs of lengths \( 6 \) and \( b \), and a perimeter of \( 18 \), follow these steps:

1. **Perimeter Equation:**
The perimeter of the triangle is the sum of its sides:
\[
6 + b + c = 18
\]
Simplifying, we get:
\[
b + c = 12 \quad \text{(Equation 1)}
\]

2. **Pythagorean Theorem:**
For a right triangle:
\[
6^2 + b^2 = c^2
\]
\[
36 + b^2 = c^2 \quad \text{(Equation 2)}
\]

3. **Substitute from Equation 1 into Equation 2:**
From Equation 1, \( b = 12 - c \). Substitute this into Equation 2:
\[
36 + (12 - c)^2 = c^2
\]
\[
36 + 144 - 24c + c^2 = c^2
\]
\[
180 - 24c = 0
\]
\[
24c = 180
\]
\[
c = \frac{180}{24} = \frac{15}{2}
\]

**Answer:**
\boxed{B}
B