CBSE Class 10 Triangles MCQs – Similar Triangles and Basic Proportionality Theorem
CBSE Class 10 Mathematics – Chapter 6: Triangles
Title: CBSE Class 10 Triangles MCQs – Similar Triangles and Basic Proportionality Theorem
Based on: Latest CBSE Board Examination Pattern (NCERT)
Q1. If two triangles have all corresponding angles equal, then they are:
Correct Answer: B. Similar
According to AAA similarity criterion, if all corresponding angles are equal, triangles are similar though not necessarily congruent.
Q2. If in ΔABC, DE || BC and AD = 3 cm, DB = 2 cm, then AE : EC equals:
Correct Answer: B. 3:2
By Basic Proportionality Theorem (BPT), AD/DB = AE/EC.
So AE/EC = 3/2.
Q3. The ratio of areas of two similar triangles is 25:16. Ratio of corresponding sides is:
Correct Answer: B. 5:4
Ratio of areas = square of ratio of sides.
√(25/16)=5/4.
Q4. In ΔABC, if AB/DE = BC/EF = CA/FD, then triangles are similar by:
Correct Answer: C. SSS
When all corresponding sides are proportional, triangles are similar by SSS similarity criterion.
Q5. If two triangles are similar, their corresponding medians are:
Correct Answer: B. Proportional
In similar triangles, all corresponding linear measures (medians, altitudes, angle bisectors) are proportional.
Q6. If DE || BC in ΔABC, then AD/DB equals:
Correct Answer: A. AE/EC
By Basic Proportionality Theorem, a line parallel to one side divides other two sides proportionally.
Q7. Two similar triangles have sides in ratio 3:5. Ratio of their perimeters is:
Correct Answer: B. 3:5
Perimeter is sum of sides; hence it follows same ratio as sides.
Q8. If corresponding sides are proportional and included angles equal, similarity criterion is:
Correct Answer: A. SAS
SAS similarity requires two sides proportional and included angle equal.
Q9. If ΔABC ~ ΔPQR, then ∠A equals:
Correct Answer: A. ∠P
Order of similarity indicates corresponding angles.
Q10. Ratio of areas of similar triangles equals:
Correct Answer: B. Square of ratio of sides
Area depends on square of linear dimensions.
Q11. In similar triangles, altitudes are:
Correct Answer: B
All linear measures are proportional.
Q12. If AB=6, BC=8 and PQ=9, QR=12, triangles are:
Correct Answer: A
6/9=8/12=2/3 → proportional.
Q13. Converse of BPT states if line divides two sides proportionally, then it is:
Correct Answer: B
This is Converse of Basic Proportionality Theorem.
Q14. If two angles of one triangle equal two angles of another, triangles are:
Correct Answer: B
AA similarity criterion.
Q15. Ratio of areas 49:64, ratio of sides?
Correct Answer: A
√(49/64)=7/8.
Q16. If ΔABC ~ ΔDEF, AB corresponds to:
Correct Answer: A
Order indicates correspondence.
Q17. In BPT, line must be parallel to:
Correct Answer: B
Line parallel to one side divides other two proportionally.
Q18. If sides are 3,4,5 and 6,8,10 triangles are:
Correct Answer: B
Each side doubled → proportional.
Q19. If scale factor is 4, area scale factor is:
Correct Answer: C
Area factor = square of 4 = 16.
Q20. If AD is median in similar triangles, ratio AD: corresponding median equals:
Correct Answer: B
All linear measures follow side ratio.
