Ch-9: Areas of Parallelograms and Triangles30 Questions
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Explanation: Congruent figures are identical in shape and size, so their areas are always equal.
2. If two figures have equal areas, then they are:
A. Always congruent
B. Need not be congruent
C. Always similar
D. Equal in perimeter
Answer: B. Need not be congruent
Explanation: Two figures can have equal areas without having the same shape (e.g., a square and a rectangle of equal area).
3. Parallelograms on the same base and between the same parallels are:
A. Equal in area
B. Unequal in area
C. Always congruent
D. Similar
Answer: A. Equal in area
Explanation: Theorem states that parallelograms on the same base and between the same parallel lines are equal in area.
4. The area of a parallelogram is given by the formula:
A. Base × Height
B. 1/2 × Base × Height
C. 2 × Base × Height
D. Base + Height
Answer: A. Base × Height
Explanation: Area of a parallelogram = base × corresponding height (altitude).
5. If a triangle and a parallelogram are on the same base and between the same parallels, the area of the triangle is ________ the area of the parallelogram.
A. Equal to
B. Half of
C. Double of
D. One-third of
Answer: B. Half of
Explanation: Area(Triangle) = 1/2 × Area(Parallelogram) when both lie on the same base and between the same parallels.
6. Triangles on the same base and between the same parallels are:
A. Equal in area
B. Congruent
C. Unequal in area
D. Similar
Answer: A. Equal in area
Explanation: Theorem states that triangles on the same base (or equal bases) and between the same parallels are equal in area.
7. The median of a triangle divides it into two triangles of:
A. Equal perimeter
B. Equal area
C. Congruent shapes
D. Unequal area
Answer: B. Equal area
Explanation: A median of a triangle divides it into two triangles of equal areas.
8. Area of a triangle is calculated using which formula?
A. Base × Height
B. 1/2 × Base × Height
C. 2 × (Base + Height)
D. Base / Height
Answer: B. 1/2 × Base × Height
Explanation: Standard formula for area of a triangle is 1/2 × base × altitude.
9. ABCD is a parallelogram. If area(ABCD) = 40 cm², then area(ΔABC) is equal to:
A. 40 cm²
B. 20 cm²
C. 80 cm²
D. 10 cm²
Answer: B. 20 cm²
Explanation: Diagonal AC divides parallelogram ABCD into two triangles of equal area. Area(ΔABC) = 1/2 × 40 = 20 cm².
10. In ΔABC, AD is a median. If area(ΔABC) = 30 cm², then area(ΔABD) is:
A. 30 cm²
B. 15 cm²
C. 60 cm²
D. 10 cm²
Answer: B. 15 cm²
Explanation: A median divides the triangle into two parts of equal area. Area(ΔABD) = 1/2 × 30 = 15 cm².
11. If a rectangle and a parallelogram stand on the same base and between the same parallels, their areas are in the ratio:
A. 1 : 2
B. 2 : 1
C. 1 : 1
D. 1 : 4
Answer: C. 1 : 1
Explanation: A rectangle is also a parallelogram. Parallelograms on the same base and between same parallels have equal areas, so ratio is 1 : 1.
12. If the base of a parallelogram is 8 cm and its corresponding altitude is 5 cm, its area is:
A. 20 cm²
B. 40 cm²
C. 13 cm²
D. 80 cm²
Answer: B. 40 cm²
Explanation: Area = Base × Altitude = 8 cm × 5 cm = 40 cm².
13. In ΔABC, D, E, F are mid-points of sides BC, CA, and AB respectively. The ratio of area(ΔDEF) to area(ΔABC) is:
A. 1 : 2
B. 1 : 3
C. 1 : 4
D. 1 : 8
Answer: C. 1 : 4
Explanation: The four smaller triangles formed by mid-points are equal in area. Hence, Area(ΔDEF) = 1/4 × Area(ΔABC).
14. Parallelogram ABCD and ΔABE lie on the same base AB and between same parallels AB and CD. If area(ΔABE) = 24 cm², find area(ABCD):
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