16Hit1600
Geometry and TrigonometryVery hardSide of a triangle from a parallel segment

Geometry and Trigonometry practice question

In triangle PQR, point S lies on side PQ and point T lies on side PR so that segment ST is parallel to side QR. If PS = 4, SQ = 6, and ST = 6, what is the length of QR?

Answer: 15

Triangles PST and PQR are similar with ratio PS/PQ = 4/10, so QR = 6 × 10/4 = 15.

Common wrong answers

If you answered 4
4 uses the ratio SQ/PS backwards.
If you answered 9
9 uses the ratio SQ/PS = 6/4.
If you answered 10
10 is PQ, not QR.

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