Page 200 - Start Up Mathematics_7

9. In ∆ ABC and ∆ DEF, BC = EF and ∠C = ∠F. The additional information required to prove
the congruency of triangles by SAS criterion is:

(a) CA = FD (b) AB = DE (c) AB = DF (d) AC = DE

solve Mentally
True or False

1. Two congruent triangles are equal in area.

2. Two triangles having equal areas are congruent.
3. Two squares having equal areas are congruent.

4. Two triangles are congruent if any three parts of one are respectively equal to the corresponding
three parts of the other.

5. Two equilateral triangles having same perimeter are congruent.
6. If two triangles are congruent by SAS criterion, then they can be proved congruent by all
other congruency criteria provided relevant data is available.

7. If two sides of a right triangle are equal to the corresponding sides of the other right triangle,
then the triangles are congruent.

8. Three angles of one triangle are respectively equal to the three angles of the other. Further any
one side of the two triangles being equal is sufficient to prove the two triangles congruent.
Fill in the Blanks

1. If ∆ RAT ≅ ∆ DOG, then the part of ∆ RAT corresponding to DG is ___________.

2. In RHS congruence rule, H stands for ___________.
3. In two congruent triangles the corresponding altitudes are ___________.

4. 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 ___________.

5. Two triangles having corresponding sides equal are ________ by _______ criterion.
For questions numbered 6 to 9 refer to the given figure D
and fill in the blanks by inserting ≅ or ≅. A

6. ∠ABC _____ ∠DEF
7. AB _____ DE

8. AC _____ EF
9. ∆ ABC _____ ∆ DEF

Answer in One Word or a Line B C E F

1. When are two triangles said to be congruent?
2. Name the different criteria to prove the congruence of two triangles.

3. What do you mean by method of superposition to check congruency?

192