IMO Practice Test — Areas of Parallelograms and Triangles
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
hard
ABCD is a parallelogram. A point E is chosen randomly inside the parallelogram. What is the sum of the areas of Triangle EAB and Triangle ECD?
1/3 Area(ABCD)
1/2 Area(ABCD)
1/4 Area(ABCD)
2/3 Area(ABCD)
Explanation: Drawing a parallel line through E shows that the sum of the heights equals the total height.
Question 2 of 6
hard
In a Triangle ABC, the medians AD, BE, and CF intersect at a single central point G (the centroid). If the total area of Triangle ABC is 72 sq cm, find the area of the small sub-triangle AGB.
12 sq cm
24 sq cm
36 sq cm
18 sq cm
Explanation: The three medians divide a triangle into six small triangles of equal area. Area = 72 / 3 = 24.
Question 3 of 6
hard
ABCD is a trapezium where side AB runs parallel to side CD. The diagonals AC and BD intersect each other at a central point O. Compare the areas of Triangle AOD and Triangle BOC.
Area(AOD) > Area(BOC)
Area(AOD) = Area(BOC)
Area(AOD) < Area(BOC)
No fixed relation
Explanation: Area(ABC)=Area(ABD) as they share base AB. Subtracting common Area(AOB) leaves equal areas.
Question 4 of 6
hard
In a Triangle ABC, points D and E are marked on side BC such that the side is split into three equal parts (BD = DE = EC). If the total area of Triangle ABC is 45 sq cm, find the area of Triangle ADE.
10 sq cm
15 sq cm
20 sq cm
22.5 sq cm
Explanation: The three sub-triangles share the same height and have equal bases, so each gets 1/3 of total area.
Question 5 of 6
hard
ABCD is a parallelogram. Points P and Q are the mid-points of sides BC and CD respectively. If you draw lines AP and AQ, what fraction of the total area of the parallelogram is the area of Triangle APQ?
1/4
3/8
1/2
5/8
Explanation: By subtracting the areas of corner triangles ABP, PCQ, and ADQ, the remaining inner area is 3/8.
Question 6 of 6
hard
In a Triangle ABC, D is the mid-point of side AB, and E is the mid-point of side AC. If a line segment DE is drawn, what is the ratio of the area of Triangle ADE to the area of the remaining quadrilateral DBCE?
1:2
1:3
1:4
2:3
Explanation: Triangle ADE has 1/2 base and 1/2 height of ABC, so its area is 1/4. Quadrilateral gets 3/4. Ratio is 1:3.