Chapter 4: Geometry
Complete Solutions for Exercise 4.1 — Class 6 Mathematics
Exercise 4.1 Solutions
1. Fill in the blanks.
Solution:
- A line through two end points 'A' and 'B' is denoted by AB with a double arrow above (↔) i.e., &overleftrightarrow{AB} .
- A line segment from point 'B' to point 'A' is denoted by BA with a bar above (‾) i.e., &overline{BA} .
- A ray has one end point(s).
2. How many line segments are there in the given line? Name them.
Solution:
There are a total of 10 line segments formed by the points P, A, B, C, and Q on the given line.
Name of the line segments:
- Starting from point P: &overline{PA}, &overline{PB}, &overline{PC}, &overline{PQ}
- Starting from point A: &overline{AB}, &overline{AC}, &overline{AQ}
- Starting from point B: &overline{BC}, &overline{BQ}
- Starting from point C: &overline{CQ}
3. Measure the following line segments.
Solution:
(Note: Exact measurements depend on the textbook scale format, standard calibrated textbook dimensions are as follows):
- XY = 2.5 cm
- AB = 3.4 cm
- EF = 4.0 cm
- PQ = 3.0 cm
4. Construct a line segment using ruler and compass.
Step-by-Step Construction Procedure:
- AB = 7.5 cm
- Draw a long straight line l and mark a point A on it.
- Place the compass pointer at the 0 mark of the ruler and extend the pencil tip to 7.5 cm.
- Keeping the compass width unchanged, place its pointer on point A and cut an arc on the line l.
- Mark the intersection point as B. &overline{AB} is the required line segment of length 7.5 cm.
- CD = 3.6 cm
- Draw a straight line m and mark a point C on it.
- Measure a width of 3.6 cm on the compass using a ruler.
- Place the compass needle on point C and mark an arc intersecting line m.
- Label this intersection point as D. &overline{CD} is the required line segment of length 3.6 cm.
- QR = 10 cm
- Draw a straight line n and mark a point Q on it.
- Set the distance between the compass pointer and pencil tip to exactly 10 cm using a ruler.
- Place the compass needle firmly at Q and draw an arc cutting the line n.
- Label the intersection point as R. &overline{QR} is the required line segment of length 10 cm.
5. From the given figure, name the: (i) parallel lines, (ii) intersecting lines, (iii) points of intersection.
Solution:
- Parallel lines:
- Line CD and Line EF (CD ∥ EF)
- Line CD and Line GH (CD ∥ GH)
- Line EF and Line GH (EF ∥ GH)
- Thus, the vertical lines CD, EF, and GH are mutually parallel to each other.
- Intersecting lines:
- Line AB intersects line CD
- Line AB intersects line EF
- Line AB intersects line GH
- Line AB intersects line IJ
- Line GH intersects line IJ
- Points of intersection:
- The points where the lines cross each other are: P, Q, and R.
6. From the given figure, name:
Solution:
- All pairs of parallel lines:
- Line l3 and Line l4 (l3 ∥ l4)
- Line l3 and Line l5 (l3 ∥ l5)
- Line l4 and Line l5 (l4 ∥ l5)
- All pairs of intersecting lines:
- Pair (l1, l2)
- Pairs involving horizontal line l3: (l1, l3), (l2, l3)
- Pairs involving horizontal line l4: (l1, l4), (l2, l4)
- Pairs involving horizontal line l5: (l1, l5), (l2, l5)
- Pair of lines whose point of intersection is 'V':
- Line l1 and Line l2 intersect at point V.
- Point of intersection of the lines 'l2' and 'l3':
- Point Q
- Point of intersection of the lines 'l1' and 'l5':
- Point T
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