4. A rectangle ABCD, which measures 9ft by 12ft, is folded once perpendicular to diagonal AC so that the opposite vertices A and C coincide. Find the length of the fold.
5. Line AC = 3, Line BC = 4, Line EF = 2
DEFG is a rectangle. ABC is a right triangle. DE is perpendicular to AB. Find the area of DEFG
4: Did you actually "cut off" a representative 9by12 rectangle (make it 3by4 inches!) to "see"?
Make EF = fold line (E on AB, F on CD) and make G intersection point of AC and EF.
Now go fold a 3by4 rectangle and see what you come up with...
5: HINT: Triangles ABC, ADE, BFG and CDG are similar right triangles; and AB = 5.
Let AE = x: then BF = 3 - x ; now have some fun...