Problem: The length of rectangle ABCD is 5 inches and its width is 3 inches. Diagonal AC is divided into three equal segments by points E and F. The area of triangle BEF, expressed in square inches, is:
Answer Choices:
A. 23
B. 35
C. 25
D. 3134
E. 3168
Solution:
The area of triangle ABC equals 21⋅5⋅3=215. Since AE=EF=FC, the area of triangle BEF equals 31 of the area of triangle ABC, that is, 31⋅215=25.