Using isosceles trapezoid knowledge to solve mathematics problems in grade three of junior high school It is known that in isosceles ABCD, ad is parallel to BC, diagonal AC is perpendicular to BD, ad = 3cm, BC = 7cm

Using isosceles trapezoid knowledge to solve mathematics problems in grade three of junior high school It is known that in isosceles ABCD, ad is parallel to BC, diagonal AC is perpendicular to BD, ad = 3cm, BC = 7cm

Let d be de / / AC and the extension line of BC intersect at e, then ad = CE, triangle DCE and ADB have the same base and height, so the area of two triangles is equal, so the area of isosceles ladder is equal to the area of triangle BDE, in triangle BDE, BD ⊥ de, ad = CE = 3, BC = 7, so be = BC + CE = 10, in isosceles straight angle triangle BDE, de = BD = be /