andy is constructing a triangle EFG congruent to triangle PQR.

An acute scalene triangle PQR.

She constructed a segment EG congruent to side PR. Next, she measured side PQ with a ruler and constructed a segment of the same length above and towards the left side of segment EG from point E. She labeled the other end of the segment as point F. What error did Sandy make in these steps?

Question

andy is constructing a triangle EFG congruent to triangle PQR.
 
An acute scalene triangle PQR.
 
She constructed a segment EG congruent to side PR. Next, she measured side PQ with a ruler and constructed a segment of the same length above and towards the left side of segment EG from point E. She labeled the other end of the segment as point F. What error did Sandy make in these steps?

directrix · Answer

If we're talking classic Greek contructions (compass and straigtedge only), Andy messed  up when she used a ruler to measure side PQ.