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Zorluk: OrtaRight Triangles and the Pythagorean Theorem

In right triangle PQRPQR, the measure of angle PQRPQR is 9090^\circ. Point SS lies on side PQPQ. If the length of side QRQR is 1515, the length of segment SRSR is 1717, and the length of segment PSPS is 1212, what is the length of side PRPR?

Cevap: 25

Cevap

The length of side PRPR is 2525.
First, the Pythagorean theorem is applied to the smaller right triangle SQRSQR to solve for the unknown leg QSQS: QS=SR2QR2=172152=8QS = \sqrt{SR^2 - QR^2} = \sqrt{17^2 - 15^2} = 8. Next, the total length of leg PQPQ is the sum of its parts, PSPS and QSQS, which gives PQ=12+8=20PQ = 12 + 8 = 20. Finally, the Pythagorean theorem is applied to the main right triangle PQRPQR to find the hypotenuse PRPR: PR=PQ2+QR2=202+152=400+225=625=25PR = \sqrt{PQ^2 + QR^2} = \sqrt{20^2 + 15^2} = \sqrt{400 + 225} = \sqrt{625} = 25.

Adım Adım Çözüm

1
Use the Pythagorean theorem on the right triangle SQRSQR to find the length of segment QSQS.
QS=8QS = 8
Triangle SQRSQR shares the right angle at QQ with triangle PQRPQR. Thus, QS2+QR2=SR2    QS2+152=172    QS=8QS^2 + QR^2 = SR^2 \implies QS^2 + 15^2 = 17^2 \implies QS = 8.
2
Determine the length of side PQPQ.
PQ=20PQ = 20
Since SS lies on side PQPQ, the length of PQPQ is the sum of PSPS and QSQS: PQ=12+8=20PQ = 12 + 8 = 20.
3
Use the Pythagorean theorem on right triangle PQRPQR to calculate the length of the hypotenuse PRPR.
PR=25PR = 25
PQ2+QR2=PR2    202+152=PR2    400+225=625    PR=25PQ^2 + QR^2 = PR^2 \implies 20^2 + 15^2 = PR^2 \implies 400 + 225 = 625 \implies PR = 25.

Anahtar Kavram

Multi-step application of the Pythagorean theorem in nested right triangles
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