Sinclair applied a dimensional change to a trapezoid with a height of 5 and base lengths 3 and 7 to determine the effect a proportional change has on the area. His work is shown below. 1. Original: A = 1 2 (3+7)(5) = 25 ft2 2. New: A = 1 2 ( 1 + 7 3 ) ( 5 3 ) = 25 9 ft2 3. Compare volumes: 25 9 25 = 25 9 ( 1 25 ) = 1 9 Use Sinclair’s work to answer the questions and complete the statements. How did Sinclair come up with the dimensions 1, 7 3 , and 5 3 in step 2? He multiplied the original dimensions by a scale factor of . What can Sinclair conclude about the effect on the trapezoid’s area from his comparison? The changes created an area times the original area.