Class 7, Maths, Chapter 7, Exercise 7.1 Solutions
Q.1. Complete the following statements:
(a) Two line segments are congruent if ___________.
(b) Among two congruent angles, one has a measure of 70°; the measure of the other angle is ___________.
(c) When we write ∠A = ∠B, we actually mean ___________.
Ans:
(a) if they have the same length
(b) 70o
(c) When we write ∠A = ∠B, we actually mean m ∠A = m ∠B.
Q.2. Give any two real-life examples for congruent shapes.
Ans:
(i) Two mobiles of same brand.
(ii) two bricks
(iii) two cubical dice
Q.3. If ∆ABC ≅ ∆FED under the correspondence ABC ↔ FED, write all the corresponding congruent parts of the triangles.
Ans:
Given that, ∆ABC ≅ ∆FED
All the corresponding congruent parts of the triangles are,
(i) ∠A ↔ ∠F
(ii) ∠B↔ ∠E
(iii) ∠C ↔∠D
(iv) $\overline{AB}\leftrightarrow \overline{FE}$
(v) $\overline{BC}\leftrightarrow \overline{ED}$
(vi) $\overline{CA}\leftrightarrow \overline{DF}$
Q.4. If ∆DEF ≅ ∆BCA, write the part(s) of ∆BCA that correspond to
(i) ∠E
(ii) EF
(iii) ∠F
(iv) DF
Ans:
If ∆DEF ≅ ∆BCA
Then, the part of ΔBCA that correspond to,
(i) ∠E ↔ ∠C
(ii) $\overline{EF}\leftrightarrow \overline{CA}$
(iii) ∠F ↔ ∠A
(iv) $\overline{DF}\leftrightarrow \overline{BA}$
