Question 255084
Draw a four sided figure (better if it looks like a rectangle or parallelogram.)
label the "corners" from 
top left A 
top right B
bottom right C
bottom left D
Draw line from A to C
Now it says that line bisects the two angles that it goes through which means  that each part that got cut by the ray(line) is equal. Angle DAB is equal to CAB and ACB is equal to DAC

 
The proof is to show that the other two angles(B and D)  are equal.(congruent)

There should be some  theorems or  postulates that talk about angles that are bisected  to help you prove it.