Question

Difficulty: MediumPythagorean Theorem and Special Right Triangles

In right triangle ABCABC, the right angle is located at vertex BB. Point DD lies on leg BCBC such that AB=12AB = 12 inches and BD=9BD = 9 inches. If segment ADAD is equal in length to segment DCDC, what is the length of leg BCBC, in inches?

Answer: 24 inches

Answer

The length of leg BCBC is 24 inches.
Applying the Pythagorean theorem to right triangle ABDABD gives AD=122+92=15AD = \sqrt{12^2 + 9^2} = 15 inches. Because segment ADAD equals segment DCDC, DCDC is also 15 inches. Adding the lengths of segments BDBD and DCDC gives BC=9+15=24BC = 9 + 15 = 24 inches.

Step-by-Step Solution

1
Calculate the length of hypotenuse ADAD in right triangle ABDABD
AD=15AD = 15 inches
Apply the Pythagorean theorem: AD=AB2+BD2=122+92=15AD = \sqrt{AB^2 + BD^2} = \sqrt{12^2 + 9^2} = 15.
2
Determine the length of segment DCDC
DC=15DC = 15 inches
It is given that segment ADAD is equal in length to segment DCDC.
3
Calculate the total length of leg BCBC
BC=24BC = 24 inches
Add the adjacent segment lengths along leg BCBC: BC=BD+DC=9+15=24BC = BD + DC = 9 + 15 = 24.

Key Concept

Applying the Pythagorean theorem to adjacent right triangles within geometric figures.
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