CBSE Class 10 Mathematics Triangles Assignment Set B

IMPORTANT CONCEPTS

TAKE A LOOK

1. Similar Triangles:- Two triangles are said to be similar, if (a) Their corresponding angles are equal and (b) Their corresponding sides are in proportion (or are in the same ratio).

2. Basic proportionality Theorem [ or Thales theorem for solution refer NCERT Text Book ].

3. Converse of Basic proportionality Theorem.

4. Criteria for similarity of Triangles.

(a) AA or AAA similarity criterion.

(b) S.A.S similarity criterion.

(c) S.S.S similarity criterion.

5. Areas of similar triangles.

6. Pythagoras theorem.

7. Converse of Pythagoras theorem.

Question. If in two triangles DEF and PQR, –D = –Q and –R = –E, then which of the following is not true?
(a) PR/EF = PQ/DF 
(b) PQ/DE = RP/EF
(c) QR/DE = PQ/DF
(d) RP/EF = QR/DE
Answer : B

Question. In ΔABC and ΔDEF, ∠B = ∠E, ∠F = ∠C and AB = 3DE. Then, the two triangles are
(a) congruent but not similar
(b) similar but not congruent
(c) neither congruent nor similar
(d) congruent as well as similar
Answer : B

Question. In the figure shown along side, DE || BC, ∠ADE = 70° and ∠BAC = 50°, then ∠BCA =

(a) 30°
(b) 60°
(c) 40°
(d) 45°
Answer : B

Question. In the figure, if ∠ACB = ∠CDA, AC = 6 cm and AD = 3 cm, then the length of AB is

(a) 8 cm
(b) 10 cm
(c) 12 cm
(d) 16 cm
Answer : C

Question. In the given figure, if DE || BC, the EC equals

(a) 1 cm
(b) 2 cm
(c) 4 cm
(d) 6 cm
Answer : B

Question. In the given figure, D and E are points on AB and AC respectively such that DE || BC. If AD = 1/3 BD and AE = 4.5 cm, then AC is equal to

(a) 12 cm
(b) 14 cm
(c) 16 cm
(d) 18 cm
Answer : D
 

Assertion-Reason Type Questions

In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Choose the correct choice as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.

Question. Assertion (A): If ΔABC and ΔPQR are congruent triangles, then they are also similar triangles.
Reason (R): All congruent triangles are similar but the similar triangles need not be congruent.
Answer : A

Question. Assertion (A): In the given figure, PA || QB || RC || SD.
Reason (R): If three or more line segments are perpendiculars to one line, then they are parallel to each other.
Answer : A