Suppose that ABCD is a trapezoid in which AD || BC. Given AC perpendicular CD, AC bisects angle BAD, and the area of ABCD is 42, then compute the area of triangle ACD.
What is the length of AD or AC? We need the length of some sides to determine what the area is. Many trapezoids that fit your description could have different side lengths, leading to different areas.
I cannot help you too much because insufficient information was given, but I can tell you that ABCD is an isosceles trapezoid. Angle ADC = Angle BCD, Angle DAB = Angle CBA. Since AC bisects angle DAB, DB also bisects angle ABC.
- PM