Page 196 - ICSE Math 7

¾ The corresponding parts of congruent triangles (abbreviated as CPCT) are equal.

¾ AAS—If two angles and a side of one triangle are equal to the two angles and the
corresponding side of the other, then the triangles are congruent. By angle sum property of a
triangle, one can show AAS leads to ASA congruency rule mentioned above.

MENTAL MATHS

1. Choose the correct answer.
(a) The symbol used to represent congruent triangles is ____________.
(i) ~ (ii) = (iii) ≅ (iv) ≈
(b) Which one of the following is not a standard criterion for congruency of triangles?
(i) SAS (ii) SSA (iii) RHS (iv) ASA
(c) Two line segments are congruent, if and only if they are ____________.
(i) perpendicular (ii) parallel (iii) equal in length (iv) unequal in length
(d) The diagonal of a rectangle divides it into two triangles that are ____________.

(i) congruent (ii) similar (iii) equal in area (iv) all of these
(e) If ∆ PQR ≅ ∆ LMN, then ____________.
(i) PQ = LM (ii) PQ = MN (iii) ∠P = ∠M (iv) ∠Q = ∠N
2. Write True or False.
(a) Two congruent triangles are equal in area.
(b) Two triangles having equal areas are congruent.
(c) Two squares having equal areas are congruent.
(d) Two triangles are congruent if any three parts of one are respectively equal to the corresponding
three parts of the other.
(e) Two equilateral triangles having same perimeter are congruent.
3. Fill in the blanks.
(a) If ∆ RAT ≅ ∆ DOG, then the part of ∆ RAT corresponding to DG is ___________.
(b) In RHS congruence rule, H stands for ___________.
(c) In two congruent triangles the corresponding altitudes are ___________.
(d) If the hypotenuse and an acute angle of one right triangle are equal to the hypotenuse and the
corresponding acute angle of another right triangle then the two right triangles are congruent
by ___________.
(e) Two triangles having corresponding sides equal are ________ by _______ criterion.

PRACTICE TIME

1. In the adjoining figure, OP is the bisector of ∠AOB. PL OB and A
PM OA. M

(a) Is ∆ POM ≅ ∆ POL? Which congruency criterion have you
used? P

(b) Find the angle corresponding to ∠LPO. Are these angles equal?
(c) Is PM = PL? O L B

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