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The hypotenuse of a [tex]$45^{\circ}-45^{\circ}-90^{\circ}$[/tex] triangle measures 18 cm. What is the length of one leg of the triangle?

A. 9 cm
B. [tex]$9 \sqrt{2}$[/tex] cm
C. 18 cm
D. [tex]$18 \sqrt{2}$[/tex] cm


Sagot :

Certainly! Let's solve the problem step-by-step.

A [tex]\(45^\circ-45^\circ-90^\circ\)[/tex] triangle is a special right triangle. In such a triangle, the two legs are equal in length, and the hypotenuse is [tex]\( \sqrt{2} \)[/tex] times the length of each leg.

Given:
- The hypotenuse is 18 cm

We need to find the length of one leg. Let's denote the length of one leg as [tex]\( \text{leg} \)[/tex].

Using the property of a [tex]\(45^\circ-45^\circ-90^\circ\)[/tex] triangle:
[tex]\[ \text{hypotenuse} = \text{leg} \times \sqrt{2} \][/tex]

Therefore:
[tex]\[ 18 = \text{leg} \times \sqrt{2} \][/tex]

Solving for [tex]\( \text{leg} \)[/tex]:
[tex]\[ \text{leg} = \frac{18}{\sqrt{2}} \][/tex]

To rationalize the denominator:
[tex]\[ \text{leg} = \frac{18}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}} \][/tex]
[tex]\[ \text{leg} = \frac{18 \sqrt{2}}{2} \][/tex]
[tex]\[ \text{leg} = 9 \sqrt{2} \][/tex]

Thus, the length of one leg of the triangle is [tex]\( 9 \sqrt{2} \)[/tex] cm.

Therefore, the correct answer is:
[tex]\[ 9 \sqrt{2} \, \text{cm} \][/tex]