The problem asks us to find the value of $x$ in the given right triangle, where the hypotenuse is 12 cm and one of the angles is 45 degrees. The side opposite to the 45-degree angle is $x$.

GeometryRight TrianglePythagorean TheoremTrigonometryIsosceles Triangle45-45-90 Triangle
2025/3/10

1. Problem Description

The problem asks us to find the value of xx in the given right triangle, where the hypotenuse is 12 cm and one of the angles is 45 degrees. The side opposite to the 45-degree angle is xx.

2. Solution Steps

Since we have a right triangle with one angle equal to 45 degrees, the other angle must also be 45 degrees (because the sum of angles in a triangle is 180 degrees, and 180 - 90 - 45 = 45). Thus, we have an isosceles right triangle, which means that the side opposite to the 45-degree angle is equal to the side adjacent to the 45-degree angle.
Let the adjacent side also be xx. Then we have a right triangle with sides xx, xx, and a hypotenuse of 12 cm.
By the Pythagorean theorem, we have
x2+x2=122x^2 + x^2 = 12^2
2x2=1442x^2 = 144
x2=72x^2 = 72
x=72=36×2=62x = \sqrt{72} = \sqrt{36 \times 2} = 6\sqrt{2}
To express xx as a decimal, we know 21.414\sqrt{2} \approx 1.414.
x=6×1.414=8.484x = 6 \times 1.414 = 8.484
We can also use trigonometry: sin(45)=x12\sin(45) = \frac{x}{12}. We know sin(45)=22\sin(45) = \frac{\sqrt{2}}{2}, so
x=12sin(45)=12×22=62x = 12 \sin(45) = 12 \times \frac{\sqrt{2}}{2} = 6\sqrt{2}

3. Final Answer

626\sqrt{2}

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