We have a right triangle with a hypotenuse of 12 cm and one angle measuring 45 degrees. We need to find the lengths of the other two sides, $x$ (opposite) and $y$ (adjacent), rounded to three decimal places.

GeometryRight TriangleTrigonometry45-45-90 TriangleSineCosine
2025/3/10

1. Problem Description

We have a right triangle with a hypotenuse of 12 cm and one angle measuring 45 degrees. We need to find the lengths of the other two sides, xx (opposite) and yy (adjacent), rounded to three decimal places.

2. Solution Steps

Since we have a 45-degree angle in a right triangle, this is a 45-45-90 triangle. However, we can also use trigonometric ratios.
First, let's find xx, which is opposite to the 45-degree angle. We can use the sine function:
sin(θ)=oppositehypotenuse\sin(\theta) = \frac{\text{opposite}}{\text{hypotenuse}}
sin(45)=x12\sin(45^{\circ}) = \frac{x}{12}
x=12sin(45)x = 12 \sin(45^{\circ})
Since sin(45)=22\sin(45^{\circ}) = \frac{\sqrt{2}}{2},
x=1222=62x = 12 \cdot \frac{\sqrt{2}}{2} = 6\sqrt{2}
Now, let's find yy, which is adjacent to the 45-degree angle. We can use the cosine function:
cos(θ)=adjacenthypotenuse\cos(\theta) = \frac{\text{adjacent}}{\text{hypotenuse}}
cos(45)=y12\cos(45^{\circ}) = \frac{y}{12}
y=12cos(45)y = 12 \cos(45^{\circ})
Since cos(45)=22\cos(45^{\circ}) = \frac{\sqrt{2}}{2},
y=1222=62y = 12 \cdot \frac{\sqrt{2}}{2} = 6\sqrt{2}
Alternatively, since it is a 45-45-90 triangle, the side opposite to the 45-degree angle is equal to the adjacent side. Therefore x=yx = y.
x=6261.41421356=8.48528137x = 6\sqrt{2} \approx 6 \cdot 1.41421356 = 8.48528137
y=6261.41421356=8.48528137y = 6\sqrt{2} \approx 6 \cdot 1.41421356 = 8.48528137
Rounding to three decimal places:
x8.485x \approx 8.485
y8.485y \approx 8.485

3. Final Answer

x=628.485x = 6\sqrt{2} \approx 8.485
y=628.485y = 6\sqrt{2} \approx 8.485

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