Step-by-step explanation:i)  (i) Two equilateral triangles with sides 1 cm and 2 cm Two squares with sides 1 cm and 2 cm (ii) Trapezium and square Triangle and PARALLELOGRAM Video Solution Question 3: State whether the following quadrilaterals are similar or not: Answer: Quadrilateral PQRS and ABCD are not similar as their corresponding sides are proportional, i.e. 1:2, but their corresponding angles are not EQUAL. Video Solution Page No 128: Question 1: In figure.6.17. (i) and (ii), DE || BC. Find EC in (i) and AD in (ii). (i) (ii) Answer: (i) Let EC = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain (ii) Let AD = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain Video Solution Question 2: E and F are POINTS on the sides PQ and PR respectively of a ΔPQR. For each of the following CASES, state whether EF || QR. (i) PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm and FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm and RF = 9 cm (iii)PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm and PF = 0.63 cm Answer: (i) Given that, PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm, FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm, RF = 9 cm (iii) PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm, PF = 0.36 cm Video Solution Question 3: In the following figure, if LM || CB and LN || CD, prove that Answer: In the given figure, LM || CB By using basic proportionality theorem, we obtain Video Solution (i) Two equilateral triangles with sides 1 cm and 2 cm Two squares with sides 1 cm and 2 cm (ii) Trapezium and square Triangle and parallelogram Video Solution Question 3: State whether the following quadrilaterals are similar or not: Answer: Quadrilateral PQRS and ABCD are not similar as their corresponding sides are proportional, i.e. 1:2, but their corresponding angles are not equal. Video Solution Page No 128: Question 1: In figure.6.17. (i) and (ii), DE || BC. Find EC in (i) and AD in (ii). (i) (ii) Answer: (i) Let EC = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain (ii) Let AD = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain Video Solution Question 2: E and F are points on the sides PQ and PR respectively of a ΔPQR. For each of the following cases, state whether EF || QR. (i) PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm and FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm and RF = 9 cm (iii)PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm and PF = 0.63 cm Answer: (i) Given that, PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm, FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm, RF = 9 cm (iii) PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm, PF = 0.36 cm Video Solution Question 3: In the following figure, if LM || CB and LN || CD, prove that Answer: In the given figure, LM || CB By using basic proportionality theorem, we obtain Video Solution (i) Two equilateral triangles with sides 1 cm and 2 cm Two squares with sides 1 cm and 2 cm (ii) Trapezium and square Triangle and parallelogram Video Solution Question 3: State whether the following quadrilaterals are similar or not: Answer: Quadrilateral PQRS and ABCD are not similar as their corresponding sides are proportional, i.e. 1:2, but their corresponding angles are not equal. Video Solution Page No 128: Question 1: In figure.6.17. (i) and (ii), DE || BC. Find EC in (i) and AD in (ii). (i) (ii) Answer: (i) Let EC = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain (ii) Let AD = x cm It is given that DE || BC. By using basic proportionality theorem, we obtain Video Solution Question 2: E and F are points on the sides PQ and PR respectively of a ΔPQR. For each of the following cases, state whether EF || QR. (i) PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm and FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm and RF = 9 cm (iii)PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm and PF = 0.63 cm Answer: (i) Given that, PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm, FR = 2.4 cm (ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm, RF = 9 cm (iii) PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm, PF = 0.36 cm Video Solution Question 3: In the following figure, if LM || CB and LN || CD, prove that Answer: In the given figure, LM || CB By using basic proportionality theorem, we obtain