RBSE Solutions Class 6 Maths Chapter 8 Basic Geometrical Concepts and Shapes More Ques

Multiple Choice Questions

 

Question 1. Complementary angle of 40° is.
(i) 0°
(ii) 50°
(iii) 90°
(iv) 140°
Answer: (ii) 50°
In simple words: A complementary angle means two angles add up to 90°. To find the complement of 40°, you subtract 40° from 90°.

🎯 Exam Tip: Always remember the definitions of complementary (adds to 90°) and supplementary (adds to 180°) angles to avoid confusion.

 

Question 2. Angle which made on bisecting ∠180° is.
(i) 30°
(ii) 60°
(iii) 100°
(iv) 90°
Answer: (iv) 90°
In simple words: To bisect an angle means to cut it exactly in half. So, half of 180° is 90°. This creates a right angle.

🎯 Exam Tip: Bisecting an angle always creates two equal smaller angles. Knowing the exact halves of common angles is helpful.

 

Question 3. Geometrical instrument, marked with 180° parts called.
(i) set squares
(ii) protractor
(iii) divider
(iv) ruler
Answer: (ii) protractor
In simple words: A protractor is a special tool used to measure angles. It has markings from 0° to 180° shaped like a semi-circle.

🎯 Exam Tip: Understand the purpose of each geometry tool: a ruler for length, a protractor for angles, a compass for circles and arcs, and set squares for drawing specific angles.

 

Question 4. It has two sharp tips.
Answer: A divider
In simple words: A divider is a geometry tool with two pointed legs, used to measure and transfer distances without drawing.

🎯 Exam Tip: Dividers are very useful for comparing lengths or transferring measurements accurately from one part of a drawing to another.

 

Question 5. A line joining the two points of circumference and passing through center of circle is called.
(i) diameter
(ii) center
(iii) radius
(iv) None of these
Answer: (i) diameter
In simple words: The diameter is the longest line that can be drawn inside a circle, going from one edge, through the exact middle, to the opposite edge. It is always twice the length of the radius.

🎯 Exam Tip: Remember that a diameter is always a type of chord, but a chord is not always a diameter. A diameter must pass through the center.

 

Question 6. Mid part of two radii of circle is called.
(i) sector
(ii) chord
(iii) circle segment
(iv) radius
Answer: (i) sector
In simple words: A sector is like a slice of pizza from a circle. It's the area enclosed by two radii and the arc between them.

🎯 Exam Tip: Distinguish a sector (area enclosed by two radii and an arc) from a segment (area enclosed by a chord and an arc).

 

Question 7. Shaded part in figure is.
(i) Chord
(ii) Semi - circle
(iii) Circumference
(iv) None of these
Answer: (ii) Semi - circle
In simple words: A semi-circle is exactly half of a full circle. It is formed by cutting a circle along its diameter.

🎯 Exam Tip: If an image is provided in the exam, clearly identify the boundaries of the shaded region to determine if it's a sector, segment, or semi-circle.

 

Question 8. When a hand of watch make whole round, then it made an angle of
(i) 90°
(ii) 180°
(iii) 270°
(iv) 360°
Answer: (iv) 360°
In simple words: A full turn, like a clock hand making one complete circle, covers an angle of 360 degrees. This is also called a complete angle.

🎯 Exam Tip: Visualize angles in terms of turns: a quarter turn is 90°, a half turn is 180°, and a full turn is 360°.

 

Question 9. Measurement of straight angle is.
(i) 180°
(ii) 270°
Answer: (i) 180°
In simple words: A straight angle looks like a straight line. It measures exactly 180 degrees.

🎯 Exam Tip: A straight angle is important as it is the basis for supplementary angles, where two angles add up to 180°.

 

Question 10. Measurement of right angle is.
(i) 60°
(ii) 45°
(iii) 90°
(iv) 180°
Answer: (iii) 90°
In simple words: A right angle forms a perfect corner, like the corner of a square or a book. It always measures exactly 90 degrees.

🎯 Exam Tip: Right angles are often marked with a small square symbol in the corner of the angle, which is a key visual clue.

 

Question 1. Fill in the Blanks
(i) When two different lines cut each other at a point, then these are called ___________
(ii) When two lines do not cut each other or intersect, these are called ___________
(iii) Two lines or more than two lines passing through a common point are called ___________
(iv) Two rays drawn from a common point, makes an ___________
(v) Circle is the shape, on which every point is at the equidistant from a certain point on its surface. This point is called its ___________ The length from center to any point on circle is called ___________
Answer:
(i) Intersecting lines
(ii) Parallel lines
(iii) Concurrent
(iv) Angle
(v) centre, Radius.
In simple words: These terms describe how lines and points relate in geometry. Intersecting lines cross, parallel lines never meet, concurrent lines meet at one point, rays form angles, and a circle has a center and a radius from the center to its edge.

🎯 Exam Tip: Know the precise definitions of basic geometric terms. Drawing a small diagram for each definition can help in understanding and recalling them quickly.

 

Question 1. Classify the following angles as acute, obtuse, right, reflex, or straight.
(a)
(b)
(c)
(d)
(e)
(f)
Answer:
(a) Acute angle
(b) Right angle
(c) Obtuse angle
(d) Reflex angle
(e) Straight angle
(f) Acute angle
In simple words: Angles are named by their size. Acute angles are less than 90°, right angles are exactly 90°, obtuse angles are between 90° and 180°, straight angles are exactly 180°, and reflex angles are greater than 180° but less than 360°.

🎯 Exam Tip: Practice identifying different types of angles by sight. An acute angle is sharp, an obtuse angle is wide, and a right angle is a perfect corner.

 

Question 2. With the help of a protractor, measure and write the measurement of following angles.
(a)
(b)
(c)
(d)
Answer:
On observing given figures without a protractor:
(a) 40°
(b) 60°
(c) 120°
(d) 135°
Measurements of angles by measuring them with a protractor:
(a) 45°
(b) 125°
(c) 123°
(d) 130°
In simple words: Sometimes you can guess an angle's size just by looking, but for exact measurements, you need a protractor. Different tools help us understand angles better.

🎯 Exam Tip: Always use a protractor for precise angle measurements. Estimation is good for a quick check, but accuracy requires the right tool.

 

Question 4. Draw any circle and mark the following.
(a) Its center
(b) A radius
(c) a diameter
(d) A sector
(e) A circle segment
(f) an internal point
(g) An external point
(h) An arc
Answer: We draw a circle, whose parts are as below.

(a) Center = O
(b) Radius = OA, OB and OC
(c) Diameter = AC
(d) Sector = OAB (Shaded area formed by radii OA, OB and arc AB)
(e) Shaded internal part covered by Chord PQ is a circle segment.
(f) Internal point of circle = M
(g) External point of circle = N
(h) Arc = AB (Red curved line between points A and B)
In simple words: A circle has many parts. The center is the middle point, the radius connects the center to the edge, the diameter goes through the center from one edge to the other, a sector is a slice, a segment is cut off by a straight line, and an arc is a piece of the circle's edge. Points can be inside or outside the circle.

🎯 Exam Tip: When drawing a circle and its parts, use clear labels for each element to show your understanding. Use different colors or shading for sectors and segments.

 

Question 5. Draw an angle of 68° with the help of protractor and bisect it with the help of compass and scale.
Answer:

Drawing an angle of 68° with the help of a protractor and bisecting it:
1. Draw a ray BC. Place the center of the protractor on point B and align the 0° mark with ray BC.
2. Mark a point A at 68° on the protractor's scale and draw a ray BA to form ∠ABC = 68°.
3. To bisect the angle, with B as the center, draw an arc that cuts rays BA and BC at points P and Q respectively.
4. Now, with P as the center and a radius greater than half of PQ, draw an arc inside the angle.
5. With Q as the center and the same radius, draw another arc to intersect the previous arc at point D.
6. Join B and D. The ray BD is the angle bisector of ∠ABC. This means ∠ABD and ∠DBC are equal, each being 34°.
In simple words: First, draw the angle using a protractor. Then, use a compass to make two arcs from the angle's corner, touching both arms. From where these arcs touch the arms, make two more arcs that cross in the middle. A line from the corner through this crossing point will split the angle exactly in half.

🎯 Exam Tip: Accuracy is key in geometric constructions. Use a sharp pencil and ensure your compass opening remains constant for the bisection arcs. Double-check the final angles with a protractor.