Page 232 - ICSE Math 7

MENTAL MATHS

1. Choose the correct answer.
(a) The number of parallel lines that can be drawn from a point outside the line to it is __________.
(i) 0 (ii) 1 (iii) 2 (iv) infinite
(b) For lines l and m to be parallel, ∠a should be equal to __________.
(i) ∠1 (ii) ∠2 2 1
(iii) ∠3 (iv) ∠4 a l
(c) A triangle which is impossible to construct has sides measuring 3
__________. 5 m
(i) 3 cm, 4 cm, 5 cm (ii) 7 cm, 8 cm, 9 cm 4
(iii) 4 cm, 6 cm, 10 cm (iv) 10 cm, 18 cm, 12 cm
(d) An angle that cannot be constructed using a ruler and compass only is __________.
(i) 15° (ii) 22.5° (iii) 37° (iv) 60°
(e) The maximum number of points at which 4 lines can intersect is __________.
(i) 3 (ii) 4 (iii) 6 (iv) 10
(f) The number of line segments that can be formed using 4 collinear points __________.
(i) 3 (ii) 4 (iii) 6 (iv) unlimited

2. Write True or False.
(a) A unique triangle with sides measuring 7 cm, 8.1 cm and 9.3 cm cannot be constructed.
(b) A unique triangle with angles measuring 60°, 1° and 119° can be constructed.
(c) A unique triangle can be constructed with measures corresponding to SAS construction
criterion.
(d) A unique triangle can be constructed with measures corresponding to AAS construction
criterion.
(e) An acute angle and length of hypotenuse is sufficient to construct a right triangle.
3. Fill in the blanks.
(a) If two angles of a triangle are unequal, then the side opposite P
the angle which is ____________ is longer. 100° 1 l
(b) If a line l is parallel to the side PQ of a triangle as shown then, 40° 40°
∠1 = ____________. Q R
(c) The ____________ angle of a triangle is equal to the sum of
the interior opposite angles.

PRACTICE TIME

1. Draw a line AB and take a point P, 4.5 cm away from it. Draw another line CD passing through
P and parallel to AB.
2. Draw any line l. Draw another line m parallel to l at a distance of 6.6 cm from it.

3. Construct a ∆ ABC in which BC = 5.5 cm, AB = 5.7 cm and AC = 6 cm.
4. Construct a ∆ ABC in which BC = 6.1 cm, AB = 5.7 cm and AC = 5.3 cm. Also draw the
perpendicular bisector of the side BC.
5. Construct an equilateral triangle each of whose side measures 6 cm. Measure each of its angle.

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