Q&A The perimeter of diamond ABCD is 16 cm, ∠ABC＝60° , the diagonal lines AC and BD intersects at point O . Find the length of AC and BD

Q&A Given the trapezoid ABCD, AD\parallel BC , AB=AD+BC , E is the midpoint of CD. Prove AE , BE bisects \angle DAB , \angle ABC respectively.

Q&A Given quadrilateral ABCD , AD \parallel BC , BD bisects ∠ADC ,CE bisects ∠BCD , intersecting AB at point E , and intersecting BD at point O Prove the distance from O to EB is equal to that from O to ED .

Q&A D, E, F, G are midpoints of sides of square ABCD. Given the areas of the three quadrilaterals, what is the area of the shaded one?