Question 10
An 8 cm by 8 cm photograph is loose inside an 18 cm by 10 cm frame ABCD. The point M remains on AD and the point N remains on BC, as shown. The source asks: “What is the area, in square centimetres, of the region inside the frame which is never covered by the photograph?” Explain the wording issue and calculate the uncovered area at any one fixed position, assuming the whole photograph is inside the frame.
Wording caution: “never covered” during motion and “uncovered at one fixed position” are different questions. The source key does not resolve that distinction. This response is manually reviewed; explain the distinction as well as the fixed-position calculation.
Wording caution: “never covered” during motion and “uncovered at one fixed position” are different questions. The source key does not resolve that distinction. This response is manually reviewed; explain the distinction as well as the fixed-position calculation.