Page 158 - Start Up Mathematics_7

9. In the given figure, if l || m, then the value of x is: 8x – 16°
l
(a) 5° (b) 6°
m
(c) 7° (d) 8° 10x – 32°

10. For line l to be parallel to m, which of the angles should be necessarily
true? w x l
(a) w = 80° (b) x = 80°

(c) y = 100° (d) z = 80° y m
z 100°
solve Mentally

True or False
1. The supplement of an acute angle is obtuse.

2. Angles of measure 50° and 150° are supplementary angles.
3. The complement of the complement of an angle is the angle itself.
4. If two parallel lines are cut by a transversal, the angles enclosed in Z shape are called alternate
interior angles.
5. Sum of measures of all the angles formed at a point is four right angles.

6. If two lines intersect at a point, then all pairs of adjacent angles are supplementary.

Fill in the Blanks

1. If two lines cut by a transversal are such that a pair of corresponding angles are not equal,
then the lines are ________________.
2. If two parallel lines are cut by a transversal, the sum of two interior opposite angles on the
same side of the transversal is ________________.

3. The ________________ angles are sometimes referred to as F-angles as they are enclosed
in that shape.
4. If two supplementary angles are made to lie adjacent to each other, they form a ______________.

5. Angles formed by two intersecting lines having no common arm are called ________________.

6. In the adjoining figure, sum of x, y
and z is ______________. y
x z
O
7. A linear pair is formed by two ________________ angles that are supplementary.

8. If the line l is parallel to m as y l
shown in the given figure, then
x equals ______________ and y x m
equals ______________. 65°

150